Slipjockey: A marketplace for buying and selling Las Vegas bet slips

In late 2010, I began talking to a very early-stage startup named Slipjockey, based in Salt Lake City. When we first started corresponding, Slipjockey was little more than a good idea coupled with some very basic technology and passionate co-founders. In the time since, Slipjockey has taken appropriate steps to bring their concept to market, including securing a favorable legal opinion and filing a patent for their technology.

The core concept of Slipjockey is ingenious. It’s a marketplace for buying and selling Las Vegas bet slips. The process starts when someone makes a bet at a licensed Nevada race and sports book. If he or she wants to sell the bet slip for whatever reason — suppose the predicted team is winning in a landslide at halftime and the slip has doubled in value — they can log onto Slipjockey and list it for sale. Another Slipjockey user may agree to buy it. The buyer takes ownership of the bet slip and he or she can keep it or resell it again to another Slipjockey user, etc. The final owner of any bet slip is paid in full directly from the sports book that originally issued the ticket.

Real-time trading on Slipjockey is similar to the action on betting exchanges like Betfair. The key difference is that all wagers must originate from a licensed Nevada race and sports book where gambling is legal.

The Slipjockey business concept grew from the notion that handicappers should have an option other that win, lose, or push. Slipjockey provides that fourth option by enabling handicappers to terminate their outcome risk, locking in a gain or avoiding a total loss prior to the end of the event. With the growth in live betting (aka “in-running betting”) around the world, and in Las Vegas courtesy of Cantor Fitzgerald, it’s clearly an option that people want.

Initially, Slipjockey is focused on launching with coverage of US football, tennis, and golf before expanding into other sports.

I’ve spoken mainly with Ryan Eads and his brother Rory, two of the co-founders. They are smart, well spoken, and tireless entrepreneurs. I have every expectation that, to the extent this idea has wings — and I believe it does — they will make it fly.

The first question you’re likely to ask is: is this legal? Indeed, that’s the first question I asked Ryan. As a pre-condition to launching, he secured a legal opinion from a former Nevada Gaming Control Board attorney that says, in effect, that because bets originate in Las Vegas and are ultimately paid out in Las Vegas, the Slipjockey exchange is legal. The attorney’s opinion is just that: an opinion, and not a guarantee. But it is convincing and credible. Certainly Slipjockey users are safe.

Currently, Slipjockey is inviting users to participate in a soft launch for trading National Football League games. To participate, create a profile at and send an email to Mention that you read my blog post and I’m sure they’ll send you an invitation containing all the details if they have spots remaining.

A professional thanks and a personal goodbye to Steve Jobs

Small Apple tribute logo, created by Mak Long

10 Print "Hello"

That line typed on an Apple II computer in my Dad’s office in the fourth grade got me hooked on computer programming, an addiction I never outgrew.

Over the years, I’ve had the pleasure of owning, using, or programming on many of Steve Jobs’s creations, including Apple II+, Macintosh IIcx, Power Mac 7100, Newton, NeXT, Powerbook, Macbook Pro, and iPhone. I’ve been a consistent Mac in the Mac-vs-PC battle since 1984 (though I admit to a brief affair in 1998: it didn’t mean anything, Steve, I swear!). Jobs himself ignited an us-versus-them fire, which smolders on today in Apple’s John Hodgman-as-PC ads, back in 1985 with one of his best quotes:

Playboy: Are you saying that the people who made PCjr don’t have … pride in [their] product?

[Jobs:] “If they did, they wouldn’t have made the PCjr.” [Playboy, Feb. 1, 1985]

Around that time, my friends and I had a running joke: “I got a PCjr,” one of us would say; “you’re going straight to hell, kid,” the other would shoot back.

Old Apple II and Power Macintosh computers
Buried treasure: Old Apple II and Power Macintosh computers, waiting to be dusted off… someday

My wife and kids (ages 7 and 4) are more recent converts, owning a Duo, an iPhone, an iPad, and two iPod Touches among them.

I’ve owned Apple stock since about 1997, my single best investment, increasing 4,460 percent. (Priceline is my second best, gaining 3,990%.)

Like Lance, I’ll never forget where I was when I learned that Steve Jobs had died. Steven Colbert told me. Live. After a hilarious taping of the Colbert Report and four performances by the artist formerly known as Mos Def (apparently a perfectionist: who knew?), Colbert ended by balancing his iPhone on his desk, letting it fall over, then telling us, “Steve Jobs died. Sorry to be the one to tell you.” To say the mood of the audience changed instantly would be an understatement. Smiling faces turned down. Cries of anguish and “oh no!” rang out from nearly everyone in the audience, a mark of how Jobs’s influence and name recognition has grown from tech hero to global cultural icon. (Colbert gave Jobs a proper tribute the next day.)

There’s a thread in our office about the extent to which perceived success or failure at the CEO level is a fooled-by-randomness trick of the mind. But there are some examples where even the strongest skeptic must admit that an organization’s success is almost surely owed to the exceptional greatness of a single individual. Warren Buffet and Coach K come to (my) mind. But Steve Jobs must be the prime example. As if ushering in the era of personal computing and computer-animated movies was not enough, Jobs continued to outdo himself year after year, with iPod, iTunes, iPhone, and, barely a year ago, iPad. Sadly, or maybe purposefully, Jobs seemed to hit his stride just as he died. As a long-time disciple of Jobs, I’m amazed at the amount of focus in his obituaries spent on gadgets he created in the last ten years.

Jobs famously advised not to spend too much time celebrating success.

I think if you do something and it turns out pretty good, then you should go do something else wonderful, not dwell on it for too long. Just figure out what’s next.
—NBC Nightly News, 2006

Those were not empty words for Jobs: it’s how he lived his own life and how he squeezed so much out of the 56 short years he was given. The early storyline of Apple pegged Steve Wozniak as the brains and Jobs as the lucky business-minded sidekick. It turns out that Jobs was way more exceptional than the 1990s nerderati — who like me relate more to Woz — gave him credit for. Jobs had the brains, the vision, and the charisma in a combination so rare I’m not the only one who can’t think of another human alive who compares. To get a taste, read or watch Jobs’s Stanford commencement speech: it’s truly brilliant, inspiring, and one of the best ways you can spend the next few minutes of your time.

To the ultimate hacker painter, the first last analog, the nerdiest salesman, the studliest genius, the most productive perfectionist, the most detail-oriented visionary, and a personal hero:

20 Print "Goodbye"

A professional goodbye and a personal thanks to Carol Bartz

My geek CEO was fired. If you’re wondering whether she deserved it, or Yahoo! is better off for it, or Roy Bostock is a doofus or dorfus, I don’t really know.* But I do have a personal story about Carol Bartz that’s indicative of the kind of CEO she was and the kind of person she is, perfect for Ada Lovelace day, a day to blog about women in science and technology who inspire you.

In May 2010, my wife Lauren was diagnosed with breast cancer. On Sunday, May 9, 2010—Mother’s Day no less—I received a phone call. “Hello?,” I said. “Hi, this is Carol Bartz,” she said. “Wow!,” I couldn’t help saying. I had never spoken to her before. She proceeded to say how sorry she was for me and Lauren, to reassure us, to ask me questions, and to answer mine.

More than a year, multiple surgeries, and six chemo sessions later, I’m happy to say that Lauren is past the worst part of the treatment and, to the best of anyone’s knowledge, cancer free. At the time, we were frightened, bewildered, and angry. To me, the most overwhelming feeling was disbelief. Was this really happening to us? It was surreal. Lauren’s strength and sheer will to keep our home life as normal as possible, and her ability to turn the ordeal into a positive is amazing and helped me cope. That my mom and Lauren’s mom went through the same thing also helped. The more we looked into it the more we realized breast cancer was everywhere—shockingly common even at Lauren’s age. (Especially in New Jersey, one of only five states in the top tier for both incidence of and mortality from breast cancer.) The calls to increase the age of first mammogram border on criminal. One silver lining for Lauren has been meeting the amazing support community of breast cancer sufferers, survivors, and their friends. They have inspired her to give back in many ways. My mom, a radiologist and ACR fellow, was herself inspired to specialize in mammography and pursue breast cancer research.

It turns out, Carol Bartz is a survivor herself and, in addition to being one of the fifty most powerful women in business, is just another member of the breast cancer support community who cares deeply. Carol had over twelve thousand employees. To take the time to call one of them on a holiday weekend to address personal problems and pain shows the kind of leader she is. (And shows the kind of bosses Preston and Prabhakar are, who thought enough to bring it to her attention.) It’s a “Yahoo! moment” and a Carol moment that I remember vividly and continues to stick out in my mind. I suspect most stereotypes of corporate and public leaders as conniving powermad ladder climbers are just that: stereotypes. But still, I’m convinced that not all—probably few—CEOs would do what Carol Bartz did. Goodbye, good luck, and, most of all: Thanks, Carol.

* I will say that I respect Carol’s willingness give her blunt assessment of the board, possibly risking $10 million to do so, and to come right out and say “I was fired” rather than hide behind “more time with family” cliches. I’m not surprised that the board gave their full confidence to her in public just two months before firing her—of course a board always has to say that they have confidence in their current CEO. I am surprised and dismayed that, at least judging by her reaction, it seems the board was also giving their confidence to her in private. That’s HR 101: No one who’s fired should be surprised.

Two upcoming NYC-area CS-econ events: AMMA & NYCE Day

  1. The Second Conference on Auctions, Market Mechanisms and Their Applications (AMMA) is next Monday and Tuesday August 22-23, 2011, at CUNY in midtown manhattan. The program, including contributed talks on school choice, prediction markets, advertising, and market design, and invited talks by market designer extraordinaire Peter Cramton and private company stock exchange SecondMarket (where millionaires buy Facebook), look to be excellent. Hope to see you there!
  2. The fourth annual New York Computer Science and Economics Day (NYCE Day) is Friday, September 16, 2011, at NYU. You have until next Friday August 26 to submit a short talk or poster. The goal of the meeting is to bring together researchers in the larger New York metropolitan area (read: DC-Boston-Chicago) with interests in computer science, economics, marketing, and business, and a common focus in understanding and developing the economics of Internet activity.

On Intrade CEO John Delaney’s death

A few words on the tragic death last May of John Delaney, the founder and CEO of prediction market company Intrade. John died near the peak of Mount Everest, climbing toward one of his life’s dreams and leaving behind a wife and three children, including one born only days before he died that he never met.

John founded Tradesports, a pre-cursor to Intrade, in 2000. Eventually, the non-sports contracts on Tradesports where spun off as Intrade, and Tradesports was shut down in 2008, in hopes of obtaining U.S. regulatory approval. I remember marveling at the technology, featuring ajax-ian magic like push updates — new bids appeared and filled bids disappeared live in a flash of color — well before its time, before we even knew what to call it.

The prediction market community embraced John, and John them. John was happy to take academics’ quixotic market ideas — like combinatorial markets, decision markets, merger markets, tax markets, or search engine markets — and float them on Tradesports or Intrade, and share back data for academic studies. I remember when we learned a Director at Intrade would speak at the first Prediction Markets Summit in 2005, we were thrilled to hear from a pioneer and innovator: one of the “big guns”. Chris Hibbert asked, “isn’t Tradesports the largest prediction market in the world?” It was hard to say: in a way, yes, it was and still is the largest market widely identified with the adjective ‘prediction’, but of course it depends how you define it: does Betfair count? Vegas? Stock options? If I recall, John himself spoke remotely at the second PM summit in New York.

Intrade became the prototypical example of a prediction market, mentioned in almost every academic paper on the subject. In 2008, Betfair, a goliath to Intrade’s David in terms of revenue and profit, got so annoyed they lashed out and sent the following attack on Intrade and defense of their own service dubbed Betfair Predicts (now shuttered):

InTrade’s election charts are republished frequently—despite continuing
problems with market manipulation.

Betfair is the world’s largest commercial prediction market with $33
Billion per year flowing through its exchange and is well known for
integrity and advanced technology…

I don’t believe I met John in person, but he and I emailed a bit, and beyond being whip smart and a fantastic entrepreneur, John was simply an incredibly nice guy. He kept repeating, at the end of nearly every email, that I must come to London so we could meet and have a beer. Talking to others, it seems I am far from alone in this standing offer from John. On the original prediction market mailing list, John Delaney was always the peacemaker: always diplomatic and rising about some surprisingly testy exchanges. He always spoke to raise the prominence of the field as a whole, ahead of his own interests with Intrade, not only believing but acting on his belief that “a rising tide lifts all boats”.

John didn’t seem like the type to seek out risk for the simple thrill of it; rather, he took calculated risks in business and life to progress. His success at work and at home attest to this. In hindsight, it’s easy to say he calculated wrong in attempting to climb Everest, but especially among prediction market proponents we know that decisions cannot be evaluated in hindsight. Decisions must be judged based on the information available at the time the decision is made. My guess is that John knew the risks and felt the climb was a gamble worth taking in an effort to achieve a long-standing goal and to accomplish a feat few others on the planet can claim.

John, you will be sorely missed, but your legacy lives on at Intrade, in the prediction market community, among your family and friends, and in the business world, sadly and suddenly now missing one of it’s great entrepreneurs with a spirit of adventure.

2011 ACM Conference on Electronic Commerce and fifteen other CS conferences in San Jose

If you’re in the Bay Area, come join us at the 2011 ACM Conference on Electronic Commerce, June 5-9 in San Jose, CA, one of sixteen conferences that comprise the ACM Federated Computing Research Conference, the closest thing we have to a unified computer research conference.

The main EC’11 conference includes talks on prediction markets, crowdsourcing, auctions, game theory, finance, lending, and advertising. The papers span a spectrum from theoretical to applied. If you want evidence of the latter, look no further than the roster of corporate sponsors: eBay, Facebook, Google, Microsoft, and Yahoo!.

There are also a number of interesting workshops and tutorials in conjunction with EC’11 this year, including:


  • 7th Ad Auction Workshop
  • Workshop on Bayesian Mechanism Design
  • Workshop on Social Computing and User Generated Content
  • 6th Workshop on Economics of Networks, Systems, and Computation
  • Workshop on Implementation Theory


  • Bayesian Mechanism Design
  • Conducting Behavioral Research Using Amazon’s Mechanical Turk
  • Matching and Market Design
  • Outside Options in Mechanism Design
  • Measuring Online Advertising Effectiveness

The umbrella FCRC conference includes talks by 2011 Turing Award winner Leslie G. Valiant, IBM Watson creator David A. Ferrucci, and CMU professor, CAPTCHA co-inventor, and Games With a Purpose founder Luis von Ahn.

Hope to see many of you there!

Crowdpark: Taking Facebook and now Florida by storm

Crowdpark logoCrowdpark is an impressive, well-designed prediction market game that’s already attracted 500,000 monthly active users on Facebook, the 11th fastest growing Facebook app in April.

It’s a dynamic betting game with an automated market maker, not unlike Inkling Markets in functionality (or even Predictalot minus the combinatorial aspect). What stands out is the flashy UI, both literally and figuratively. The look is polished, slick, refreshing, and richly drawn. It’s also cutesy, animation-happy, and slow to load. Like I said, Flash-y in every way. The game is well integrated into Facebook and nicely incorporates trophies and other social rewards. Clearly a lot of thought and care went into the design: on balance I think it came out great.

Crowdpark is a German company with an office in San Francisco. In addition to their Facebook game, they have German and English web versions of their game, and white-label arrangements with gaming companies. They launched in English just last December.

Crowdpark’s stunning growth contrasts with decidedly more mixed results on this side of the Atlantic. I wonder how much of Crowdpark’s success can be attributed to their German roots, their product, their marketing, or other factors?

Crowdpark has an automated market maker they call “dynamic betting” that I can’t find any technical details about [1]. Here’s their well-produced video explanation:

They say it’s “patent pending”, though my colleague Mohammad Mahdian did some nice reverse engineering to show that, at least in their Facebook game, they’re almost certainly using good-old LMSR. Here is a graph of Crowdpark’s market maker price curve for a bet priced at 1%:

Crowdpark's automated market maker price curve

Here is the raw data and the fit to LMSR with b=20,000.

risk   to win (CP)   to win (LMSR)
1 91 91.079482
2 181 181.750593
5 451 451.350116
10 892 892.847929
20 1747 1747.952974
50 4115 4115.841760
100 7535 7535.378665
200 13019 13019.699483
500 23944 23944.330406
600 26594 26594.687310
700 28945 28945.633048
800 31059 31059.076097
900 32979 32979.512576
1000 34740 34740.000000

Still, there’s a quote buried in the video at 0:55 that caught my attention: “you’re current profit is determined by the fluctuation of the odds”.

There’s only one market maker that I know of where the profit fluctuates with the odds, and that’s my own dynamic parimutuel market, which by coincidence recently went from patent pending to inventor cube delivered. :-)

David Pennock's dynamic parimutuel market (DPM) patent cube - 4/2011

With every other market maker, indeed almost every prediction market, the profit is fixed at the time of the bet. Add to that the fact that Crowdpark bought a majority stake in Florida horse racing circuit Saratoga Racing Inc. and plans to operate all bets exclusively through their system, leads me to wonder if they may have some kind of parimutuel variant, the only style of betting that is legal in the US.

Of course, it may be that I simply misinterpreted the video.

[1] The technical exec at Crowdpark seems to be Aleksandar Ivanov. I found a trade press paper on (internal) prediction markets he wrote in 2009 for the Journal of Business Forecasting.

Four free registrations to EC’11 for students

Thanks to a generous donation from Google, we are offering four free registrations for students to attend the 2011 ACM Conference on Electronic Commerce (EC’11) in San Jose.

To apply, please email David Pennock and Yoav Shoham by Wednesday May 11, 2011, with subject “YourLastName: EC’11 student registration award application” and include:

  1. Your name, university, personal homepage, and current student status (e.g., 2nd year Ph.D. student)
  2. Whether you are a member of ACM SIGecom
  3. Any papers at EC’11 for which you are an author or co-author
  4. Any papers at an EC’11 affiliated workshop (or under review) for which you are an author or co-author
  5. Please also arrange for your academic advisor to email verification of your student status in good standing to the same two email addresses with your last name in the subject.

Applications must be submitted by Wednesday May 11, 2011. We will award the four free registrations by Friday May 13, prior to the early registration deadline of May 16.

David Pennock, Chair ACM SIGecom
Yoav Shoham, General Chair, EC’11

P.S. This was announced on April 14 on the mailing list for the ACM Special Interest Group on Electronic Commerce (SIGecom). If you missed it, you should join! :-)

There’s a new oracle in town

Cantor Gaming mobile device for in-running bettingLast January, a few friends and I visited the sportsbook at the M Casino in Las Vegas, one of several sportsbooks now run by Cantor Gaming, a division of Wall Street powerhouse Cantor Fitzgerald. Traditional sportsbooks stop taking bets when the sporting event in question begins. In contrast, Cantor allows “in-running betting”, a clunky phrase that means you can bet during the event: as touchdowns are scored, interceptions are made, home runs are stolen, or buzzers are beaten. Cantor went a step further and built a mobile device you can carry around with you anywhere in the casino to place your bets while watching games on TV, drink in hand. (Cantor also runs spread-betting operations in the UK and bought the venerable Hollywood Stock Exchange prediction market with the goal of turning it into a real financial exchange; they nearly succeeded, obtaining the green light from the CFTC before being shut down by lobbyists, er, Congress.)

Back to the device. It’s pretty awesome. It’s a Windows tablet computer with Cantor’s custom software — pretty well designed considering this is a financial firm. You can bet on the winner, against the spread, or on one-off propositions like whether the offensive team in an NFL game will get a first down, or whether the current drive will end with a punt, touchdown, field goal, or turnover. The interface is pretty nice. You select the type of bet you want, see the current odds, and choose how much you want to bet from a menu of common options: $5, $10, $50, etc. You can’t bet during certain moments in the game, like right before and during a play in football. When I was there only one game was available for in-running betting. Still, it’s instantly gratifying and — I hate to use this word — addictive. Once my friend saw the device in action, he instantly said “I’m getting one of those”.

When I first heard of Cantor’s foray into sports betting, I assumed they would build “betfair indoors”, meaning an exchange that simply matches bettors with each other and takes no risk of its own. I was wrong. Cantor’s mechanism is pretty clearly an intelligent automated market maker that mixes prior knowledge and market forces, much like my own beloved Predictalot minus the combinatorial aspect. Together with their claim to welcome sharps, employing a market maker means that Cantor is taking a serious risk that no one will outperform their prior “too much”, but the end result is a highly usable and impressively fun application. Kudos to Cantor.

P.S. Cantor affectionately dubbed their oracle-like algorithm for computing their prior as “Midas”, proving this guy has a knack for thingnaming.

FBI seizes gambling domain names. Who’s next?

Michael Mitzenmacher recently made a “First they came…” argument, and now I will too.

Even if you detest gambling, this should send a chill down your spine: the FBI seized the domain names of several poker websites who operate offshore and arrested their owners.

The action exposes the lie that the US government does not control the Internet or does not exercise that control and perhaps hastens the day of a fragmented Internet. It’s an example of the government’s hypocritical position on Internet freedom: how can we express outrage at countries that block facebook or censor google when our own country seizes domain names and, in another recent example, tries to pass an Internet Blacklist Bill to block file-sharing websites? To the hundreds of thousands who spoke out against the latter, kudos, but I submit that the former poses just as dangerous a slippery slope.

These companies are obeying the laws of the countries in which they are based. Who are we to block them let alone seize their Internet property?

Update 2011/05/11: More scary developments in net censorship.

Musings of a computer scientist on predictions, odds, and markets