Tag: Sam Bankman-Fried

SBF Was Reckless From the Start

Mary Pat Campbell

Link: https://www.bloomberg.com/opinion/articles/2023-10-04/sbf-was-reckless-from-the-start?srnd=undefined#xj4y7vzkg

Excerpt:

First: “A Jane Street intern had what amounted to a professional obligation to take any bet with a positive expected value”? Really? I feel like, if you are a trading intern, you are really there to learn two things. One is, sure, take bets with positive expected value and avoid bets with negative expected value.

But the other is about bet sizing. As a Jane Street intern, you have $100 to bet each day, and your quasi-job is to turn that into as much money as possible. Is betting all of it (or even $98) on a single bet with a 1% edge really optimal?[6] 

People have thought about this question! Like, this is very much a central thing that traders and trading firms worry about. The standard starting point is the Kelly criterion, which computes a maximum bet size based on your edge and the size of your bankroll. Given the intern’s bankroll of $100, I think Kelly would tell you to put at most $10 on this bet, depending on what exactly you mean by “this bet.”[7] Betting $98 is too much.

I am being imprecise, and for various reasons you might not expect the interns to stick to Kelly in this situation. But when I read about interns lining up to lose their entire bankroll on bets with 1% edge, I think, “huh, that’s aggressive, what are they teaching those interns?” (I suppose the $100 daily loss limit is the real lesson about position sizing: The interns who wipe out today get to come back and play again tomorrow.) 

But I also think about a Twitter argument that Bankman-Fried had with Matt Hollerbach in 2020, in which Bankman-Fried scoffed at the Kelly criterion and said that “I, personally, would do more” than the Kelly amount. “Why? Because ultimately my utility function isn’t really logarithmic. It’s closer to linear.” As he tells Lewis, “he had use for ‘infinity dollars’” — he was going to become a trillionaire and use the money to cure disease and align AI and defeat Trump, sure — so he always wanted to maximize returns.

But as Hollerbach pointed out, this misunderstands why trading firms use the Kelly criterion.[8] Jane Street does not go around taking any bet with a positive expected value. The point of Kelly is not about utility curves; it’s not “having $200 is less than twice as pleasant as having $100, so you should be less willing to take big risks for big rewards.” The point of Kelly is about maximizing your chances of surviving and obtaining long-run returns: It’s “if you bet 50% of your bankroll on 1%-edge bets, you’ll be more likely to win each bet than lose it, but if you keep doing that you will probably lose all your money eventually.” Kelly is about sizing your bets so you can keep playing the game and make the most money possible in the long run. Betting more can make you more money in the short run, but if you keep doing it you will end in ruin.

Author(s): Matt Levine

Publication Date: 4 Oct 2023

Publication Site: Bloomberg

FTX’s collapse mirrors an infamous 18th century British financial scandal

Mary Pat Campbell

Link: https://theconversation.com/ftxs-collapse-mirrors-an-infamous-18th-century-british-financial-scandal-196729

Excerpt:

The Charitable Corporation was established in London in 1707 with the noble mission of providing “relief of the industrious poor by assisting them with small sums at legal interest.”

Essentially, it sought to provide low-interest loans to poor tradesmen, shielding them from predatory pawnbrokers who charged as much as 30% interest. The corporation made loans available at the rate of 5% in return for a pledge of property for security.

The Charitable Corporation was modeled on Monti di Pietà, a charitable institution of credit established in Catholic countries during the Renaissance era to combat usury, or high rates of interest.

Unlike the Monti di Pietà, however, the British version – despite its name – wasn’t a nonprofit. Instead, it was a business venture. The enterprise was funded by offering shares to investors who, in return, would make money while doing good. Under its original mission, it was like an 18th century version of today’s socially responsible investing, or “sustainable investment funds.”

….

There are several key characteristics that stand out in the collapses of both the Charitable Corporation and FTX. Both companies were offering something new or venturing into a new sector. In the former’s case, it was microloans. In FTX’s case, it was cryptocurrency.

Meanwhile, the management of both ventures was centralized in the hands of just a few people. The Charitable Corporation got into trouble when it reduced its directors from 12 to five and when it consolidated most of its loan business in the hands of one employee – namely, Thomson. FTX’s example is even more extreme, with founder Sam Bankman-Fried calling all the shots.

Author(s): Amy Froide

Publication Date: 21 Dec 2022

Publication Site: The Conversation