Bond Trading Bots, Getting Smarter, Power Through Market Unrest

Wall Street has a familiar gripe about the bots that now handle a growing share of trading in the corporate bond market: they are there to buy and sell your bonds, right up until you really need them.

In periods of severe market stress, these computer-driven programs, known as algos, have historically struggled to keep up with unpredictable price moves and have stepped back at key moments, making it more expensive to trade. But lately, there are signs that the algos are learning to stay online even when volatility spikes.

The most recent test came in April, when Donald Trump’s ...