MacAskill told Bankman-Fried more about another one of his ideas: “earning to give.” He said that for someone of Bankman-Fried’s mathematical talents, it might make sense to pursue a high-paying job on Wall Street, then donate his earnings to charity.

For three years after graduation, he worked as a trader and every year gave away about half of his six-figure salary to animal-welfare groups and other effective-altruism-approved charities.

Capital controls prevented traders from sending cash home from South Korea, where Bitcoin sold for 30% more than in the U.S. But in Japan, which didn’t have those rules, Bitcoin still traded at a 10% premium. In theory, someone could earn 10% every day by buying Bitcoin on a U.S. exchange and sending it to a Japanese one to sell. At that rate, in a little more than four months, $10,000 would turn into $1 billion.

Once Bankman-Fried found willing banks, each day became a race.

At the peak, Alameda was sending $15 million back and forth daily and generating a $1.5 million profit. Within a few weeks, before the price difference disappeared, the company had earned about $20 million.

It took Bankman-Fried’s crew four months to write the code underlying a new exchange, which opened for business in May 2019.

Customers could borrow up to 101 times their collateral—slightly higher leverage than offered by the competition.

Alameda, which he no longer runs day to day, made an additional $1 billion in profit in 2021 alone.