Uber's listing was expected to be the largest in a string of public debuts by highly valued Silicon Valley companies, including apartment-renting company Airbnb and workplace messaging firm Slack, with estimates the IPO could value the company at as much as $US120 billion.

In an emailed statement, the SEC wrote: "Prior to the shutdown taking effect, we encouraged filers to reach out to us to ask for acceleration of the effectiveness of pending registration statements, and we declared approximately a dozen registration statements effective."

The US shutdown has left hundreds of thousands of workers furloughed or instructed to work without pay.

It's poised to impact deals of all sizes. Drug company Eli Lilly & Co. said on Tuesday that the SEC is creating "a problem" for the company's plan to sell stock in a unit it spun off last year.

Also on Tuesday, a pair of oil companies postponed the termination date of a $US900 million merger, citing the shutdown.