(Cross-posted from https://news.manifold.markets/p/interview-with-1-leaderboard-bettor)

Some additional context for EAs less familiar with Manifold Markets... We are a prediction market website that are looking to make forecasting go mainstream! Our approach is to gamify prediction markets, prioritise their social features, and lower the entry barrier. We love working with EAs and hope that our markets can empower everyone to make more informed decisions. To that end, we have made it so you can embed our markets on various sites including this one! 

We recently hosted Mexifold where we invited our users and EA enthusiasts to come together for 2 weeks! We are also looking forward to meeting everyone at EA Global: Washington DC this September!

We are also looking to match donations to non-profits through our site! We would love to hear from you if you want your organisation to be featured!

Today we want to share an interview we conducted with ranked one leaderboard bettor Joel Becker! Joel rose to prowess and was at the top of the leaderboard only a few weeks after joining Manifold thanks to his market manipulation strategies.

Brief background on Joel:

• Works at FTX Foundation and runs the EA fellows and visitor programme in Nassau. This was where we first met him!
• Maintained a social media presence from which he donated all of the revenue to charity. Wanting to leverage his audience to raise even more led to researching the best charities, which caused him to be sucked into the EA community.
• Learn more about Joel’s background on his website and his Twitter.

How did you first start using Manifold?

Joel: “The Manifold team were invited to the program I run at FTX. I had heard of Manifold previously through Scott Alexander’s Mantic Monday’s newsletters — more or less as the crazy prediction site that lets you bet on anything — but not yet made the jump. A combination of meeting the team and a sense of competition with my peers lead me to start using the platform.”

See if you can spot Joel and the five Manifold members amongst the other EA Fellows and visitors!

What are your main motivations for using Manifold?

Joel: “In the unusual world in which I find myself, for better or worse, doing well on a prediction markets website is somewhat of a badge of honour. Metaculus is already a well-established website; there’s no chance I can start topping it. Manifold, on the other hand, is a very well executed platform with integrations with the EA forum. Betting on Manifold is the higher-EV route to tongue-in-cheek social prestige. I wish I had more noble motivations but, alas, I think that’s a good chunk of it.”

Interviewer: “I suspect a lot of users coming to our site will be in that category of wanting to outperform their friends. It’s a use case we are planning to start tailoring our website more towards. As part of that we are adding ongoing daily, weekly, and monthly leaderboards!”

Joel: “Oh, that’s terrible! Before there was only one leaderboard and I was winning on it!

“Another important motivation for me using Manifold relates to charitable giving. As an undergraduate, I gave a pretty large fraction of my income to charity, as a graduate student I donated very little, but now being in a proper job I can afford to start donating quite a bit more again.

I think that “trying to learn about the future” is currently a very minor motivator for me. But I can imagine it being a much larger part of the motivation at some later point.”

The Charity Prediction Market

Within the first week of using the site, Joel was sitting comfortably in the middle of the leaderboard. This was partially thanks to his astute betting, but insider opportunities that presented themselves whilst being with the Manifold team in Nassau helped!

The vector that propelled him to the top of the leaderboard was his profitability on predicting how much money would be donated in June to charity after donating $4,200 last minute! We were curious to learn more about his strategy and how he executed his plan so successfully. One thing to note is that betting was effectively anonymous when this took place, although Joel isn’t convinced that things being public would have changed much.

Interviewer: “Were you always intending to donate in the ballpark of $4000, or did you only donate that much because you wanted to change the answer of the market to $5000-10,000?”

Joel: “Do you remember the total that ended up being donated? It was $5004. So what do you think the answer is (we both had a good laugh at this)! The truth is, I realised that the problem with making it big on Manifold is that there are some markets in which I felt I had an edge in and others that have high enough volume to make a profit. The intersection between these markets is very small… but here it was! This massive, easy-to-manipulate market right on the front page of Manifold, which aligned with my personal goals of wanting to donate more to charity.”

Charity Market Manipulation Breakdown

He then proceeded to break down his strategy and what happened, which we will summarise in bullet points alongside some quotes from Joel.

• He linearly extrapolated how much was being donated to charity. After the first week it was estimated at $1000 (and later around $700).
• Push the $0-500 answer to 0% as anyone betting on that is giving you free money.

Joel, “And then I realised, do I want to donate the marginal hundreds of dollars to GiveWell? Well, of course I do!”

• Slowly push the $500-1000 answer to 0%.

Joel, “You don’t want to alert people to the manipulation too early. You can see starting from mid May I began pushing down $500-1000. If I pushed it to 1% then people would clearly see what was going on. I wanted them to think it was just stupid pricing, so I push it down reasonably low and slowly bring $1000-5000 up over time.”

• Started buying 5% of the answers $10-25k and $25k+ to hedge against others pursuing similar strategies.
• Other people notice the manipulation and start betting on $1000-5000 themselves.

Joel, “And then you realise somewhere along that journey, do I want to donate $4000 to GiveWell? Yes! The answer is clearly yes!!! Now there is this ginormous pool of everything less than $5000 to take advantage of.”

1. Slowly sell $1000-5000 for profit. Buy up all of $5000-10,000.
2. Try to sow uncertainty. Is everything a house of cards and users think they should bet on $1000-5000? At the same time, bluff and continue the pattern for the next range of answers, $10,000-25,000, to have users start buying up those shares above what Joel is planning to donate.
3. At the last second, sell all answers in the wrong categories and donate however much is needed to hit the $5000-10,000 range.

Joel, “The thing that seems optimal ex-post was for me to have sold all my shares above $10,000, which I still held a lot of. But I was nervous that some people would put in a couple thousand each at the end and push it above $10,000.”

Joel's total profits on this market were 30,332 Mana (the equivalent of $303 if he were to donate it to charity). He only recuperated a fraction of what he donated, but he achieved his two primary goals of donating to charity and outperforming his friends (and everyone on Manifold for that matter)!

What changes would you like to see made to the site?

Finally, we wrapped up the interview by asking him what features he would really enjoy using if they were added to Manifold. Here is a list of his suggestions:

• Order books (limit orders) - which we have since launched!
• Integrations for mobile apps or Slack.
• Thoughts on removal of free daily markets: apprehensive as a lot of his markets are personal ones. Wouldn’t be worth the cost for him to make it on Manifold as opposed to doing it himself off-site since he doesn’t expect enough people to bet on it.

Thanks so much Joel for taking the time to talk to us! We eagerly await his return to the top of the leaderboard and look forward to seeing the rest of you challenging him!

Interview and writeup by David Chee