If Congress doesn't reopen the government soon, investors will lose part of the critical safety net that protects their trades and funds.
The Securities and Exchange Commission, which is in charge of regulating Wall Street, may have to furlough workers, suspend some investigations and even postpone stock market debuts.
That's according to the agency's contingency plan for working through a government shutdown. The latest one began Saturday after Congress failed to pass a spending bill.
Such measures would be a first for the agency, which has been able to work at full force during previous government shutdowns.
But that's because most of those shutdowns happened in the fall, when the SEC still had money on hand from the previous year.
For example, during the fall 2013 shutdown, the agency said it had enough cash to stay open for "several weeks," according to the Wall Street Journal.
This time, though, the SEC said on its website that it would be able to "remain open for a limited number of days."
A spokesperson declined to say exactly how much money the agency has on hand, or how long the SEC can keep operating normally without a new appropriation.
According to the SEC's plan, it would have to furlough all employees deemed "non-essential." As few as 300 of the more than 4,000 employees would keep coming to the office, according to the plan.
The skeleton staff "will attempt to respond to certain critical matters, including allegations of ongoing fraud and misconduct," the plan says.
For example, the SEC will monitor tips and complaints, and it will deal with "ongoing litigation that cannot be deferred."
But the plan adds that there would be "only a limited number of staff on duty to perform critical functions."
One possible casualty: initial public offerings. If a backlog of pre-IPO paperwork piles up, that could delay plans for some companies to go live on the stock market.
Meanwhile, the SEC's online tool for accessing financial disclosure forms likely won't be affected.
The website, Edgar, is operated through a contractor. SEC's plan says it would "remain fully functional as long as funding for the contractor remains available." The SEC typically signs multi-year contracts for Edgar, so the site isn't likely to go offline anytime soon.
New routine financial disclosure forms would continue to show up on the site. But anything that requires the SEC staff to review, such as IPO paperwork, will not be processed.