Last night an Intrade trader found and exploited a bug in my Automated Market Maker, manipulating DEM.PRES-TROOPS.IRAQ until Intrade rejected one of the market maker’s orders for lack of credit and the software shut down.
The bug involves handling of partial executions of orders, and doesn’t appear to be easily fixable (what happened looks nearly identical to the scenarios I had analyzed and thought I had guarded against).
For the moment, I’ve reduced the market maker’s order size to one contract, which will prevent further exploitation but provide much less liquidity.
I will try to fix the bug sometime in November and increase the order size (on the contracts that don’t get expired at election time) by as much as I can without adding more money to the market maker’s account. I will also analyze the information provided by the markets shortly after the election.
Archive for October, 2008
Automated Market Maker Problems
Sunday, October 26th, 2008
None of the above for president
Tuesday, October 21st, 2008I had been half-heartedly planning the past few months to vote for Libertarian presidential candidate Bob Barr. I had previously considered voting for Obama when it looked like he would make an important difference in the Iraq war, but it now looks like the Iraqi government will persuade the U.S. to leave soon enough for that difference not to matter. If I lived in a swing state and the election was close, I might persuade myself that Obama’s personality and intelligence make him more qualified, but my track record for evaluating politicians that way is sufficiently unimpressive that I ought to be uncertain whether I’ve been fooled by his eloquence.
Voting Libertarian is normally the best way to encourage whoever wins to adopt a better policy, but this time it’s unclear whether that would send the message “I want more unprincipled opportunists”. Barr’s past support for the war on some drugs and his current mixed opinions on that subject are damaging the Libertarian party’s reputation.
The final straw that has convinced me not to vote for him is in this New Yorker piece:
For Barr, the terrorist attacks of September 11, 2001, and the subsequent expansion of executive power under President Bush, were a political turning point. “I went through Reagan National after 9/11, and saw guardsmen with automatic weapons,” he told me. “It dawned on me that we’ve entered a whole new world. It may have made other passengers feel more secure, but it made me feel dramatically less free.”
An NRA director saying the presence of armed men is a threat to freedom? There’s no shortage of dishonest pretenses of security that directly interfere with the average passenger. I haven’t heard any indication that armed guardsmen in airports do anything to innocent people. I saw more armed soldiers in the Zurich airport in the late 1980s than I saw in U.S. airports, and I’m fairly sure they didn’t erode Swiss freedom.
This is sufficiently bizarre as to suggest he can’t keep track of which ideology he believes today.
Not to mention this older report where he seems to specifically say Reagan National should have armed guardsmen.
Seasteading08
Tuesday, October 14th, 2008The first Seasteading conference went rather well. It got a good turnout of intelligent people, in spite of being on a weekday (they didn’t plan far enough ahead to find a good weekend spot).
I was somewhat disappointed by the time spent on the basic motivations behind seasteading (do people come to this kind of conference without understanding the motivations?), and I wanted to focus more on a serious analysis of how close the business plans are to being a good investment.
One interesting idea that was briefly mentioned is unmanned farms, herded by small robotic boats. If you’re willing to lose farms to an occasional storm, that drastically cuts costs. But when I imagine the cheapest possible farms, it seems the plants would get significant salt spray, which drastically limits the types of crops which will thrive.
The most interesting subject was Ephemerisle. Before the conference I had been wondering whether it would be interesting enough that I would want to attend. The conference convinced me that it will attract the kind of people I like, and that there will be some interesting technical challenges. Since my very rusty knowledge of sailing seems to leave me better informed than most seasteaders about some of those challenges, I will want to provide some help with the planning. It’s still too poorly thought out for me to feel confident that it will be done safely, but it can probably be planned well enough to be safe under most conditions (and hopefully people will be prepared to cancel it if unusual winds make it look unsafe).
The location seems very uncertain, and will have some important impacts on the risks. During the conference, the tentative plan seemed to be a few miles of the southern California coast, but afterward I got some indications that the plan had changed to the San Francisco bay, which would be a good deal easier but which would do less to promote any long-term vision.
Misbehavior of Markets
Sunday, October 5th, 2008Book review: The Misbehavior of Markets: A Fractal View of Risk, Ruin & Reward by Benoit Mandelbrot.
Mandelbrot describes some problems with financial models that are designed to provide approximations of things that can’t be perfectly modeled. He pretends that pointing out the dangers of relying too much on imperfect approximations shows some brilliant insight. But mostly he’s just translating ideas that are understood by many experts into language that can be understood by laymen who are unlikely to get much value out of studying those ideas.
His list of “ten heresies” is arrogantly misnamed. Sure, there are some prestigious people whose overconfidence in financial models leads them to beliefs that are different from his “heresies”, but those “heresies” are closer to orthodoxies than they are to heresies.
His denial of the equity premium puzzle is fairly heretical, but his argument there is fairly cryptic, and relies on suspicious and poorly specified claims about risk.
He says market timing works, but the strategy he vaguely hints at requires faster reaction times than are likely to be achieved by the kind of investor this book seems aimed at.
His use of fractals doesn’t have any apparent value.
Mandelbrot is primarily a mathematician with limited interest in understanding how markets work. One clear example is his mention of a time when Magellan “was still a small fund, too small for any detractors to argue that its size alone gave it a competitive edge”. Any informed person should know that’s completely backward – larger funds have a clear disadvantage because they are limited to trading the most liquid investments.
Another example of a careless mistake is when he claims the evidence suggests basketball players have hot streaks, seemingly unaware that Tversky and others have largely debunked that idea.