[JayBallentine]

Can't short an IPO.

[Ocean Financing]

Can't short an IPO.

On the day of the IPO, two main parties hold inventory of the stock: the underwriters and institutional and retail investors. As determined by the Securities and Exchange Commission, which is in charge of IPO regulation in the U.S., the underwriters of the IPO are not allowed to lend out shares for short sale for 30 days. On the other hand, institutional and retail investors can lend out their shares to investors who want to short them.

However, only a limited amount of shares would probably be available on the market as the company would've just started trading publicly and the shares may not have been completely transferred. Furthermore, there might be a lack of willingness among investors to lend their shares out to be short sold.

So, while there are regulatory and practical obstacles to doing it, it is still possible to short sell shares in a company the same day the company goes public.