On what data is a new stock-trading bot basing all of its decisions?

Trends show that when President Trump tweets something positive about a company, the company’s stock price tends to go up, and the reverse is true as well. To test this, NPR’s Planet Money team has created BOTUS, a bot that will play the stock market — with real money — buying and selling based only on the president's tweets.

When Trump says something good about a certain company, BOTUS — Bot of the United States, after its source data, @POTUS — will buy that company’s stock. If he says something negative, BOTUS will sell shares of that stock, betting that its value will go down.

The public radio show worked with a firm that builds such stock-trading bots to teach BOTUS three criteria: sentiment analysis, or whether a tweet is positive or negative; a context algorithm, to determine whether the president is talking about a company at all; and how long after Trump tweets to buy or sell the relevant stock. BOTUS started trading on Friday with $1,000 of the Planet Money reporters’ personal funds, and will be posting its progress on Twitter.