Activity in the options market, particularly the riskiest bets expiring in just hours, has been booming lately.

On Thursday, traders turned to zero-day-to-expiry options-known as "0dte" trades, tied to major indexes like the S&P 500 and Nasdaq. Seven out of 10 of the most actively traded one-day options were puts tied to those two indexes, according to the data provider QuikOptions.

Puts give the right to sell shares at a specific price, by a stated date. They can be used to make directional wagers or hedge portfolios.