Corporate insiders raced to buy shares of their own companies after last month’s banking crisis, signalling a vote of confidence in this year’s market rebound.

More than 1,000 officers and directors at more than 600 companies bought their own stock in March. That is the highest number on an individual and company basis since last May, according to the Washington Service, an insider-trading data analytics provider. The ratio of insider buying to selling last month swelled to the highest level since September, the firm found.