Securities and Exchange Commission Chairman Gary Gensler said Wednesday that the regulator is eyeing tighter disclosure deadlines for hedge funds building sizable stakes in companies.

The agency is considering changing the rules under which hedge funds disclose that they have acquired 5% of a public company’s stock, Gensler said during a virtual Q&A at the Exchequer Club.

The so-called Schedule 13-D filing is currently set at 10 days, which gives hedge funds more than a week to keep buying in secret.

“I would anticipate we’d have something on that,” Gensler said, adding that he is worried about “information asymmetry,” because the public doesn’t know there’s a big player buying up shares during the 10-day period.

“Right now, if you’ve crossed the 5% threshold on day one, and you have 10 days to file, that activist might in that period of time, just go up from five to 6% or they might go from five to 15% but there’s nine days that the selling shareholders in the public don’t know that information,” Gensler said.

The 13D disclosure rule was passed in the 1960s to protect corporate managements by informing them of activities from activist shareholders and corporate raiders. In other words, big investors won’t be able to accumulate big stakes in secret to take over a company without giving it a chance to defend itself.

Critics of the rule have claimed that the 10-day deadline is already too tight and that hedge fund managers have a tougher time making a profit if they must reveal their strategies to the public so soon.

“It’s material nonpublic information that there’s an activist acquiring stock, who has an intent to influence and generally speaking, there’s a pop if you look at the economics from the day they announced … there’s usually a pop in the stock at least single-digit percent,” Gensler said. “So the selling shareholders during those days don’t have some material information.”