Key Takeaways Retail investors today have more access to pre-initial public offering (IPO) shares thanks to offerings from brokerages, including Robinhood (HOOD) and SoFi (SOFI). You can sell shares on a stock's first day of trading, but it's considered "flipping" and firms have penalties in place to discourage it. The brokerages are allocated a portion of IPO shares, which are then randomly distributed to the pool of interested investors. Important Stocks don't always rise on their first day of trading, and even those that do often fall below their IPO price within weeks of going public. Investors can sell IPO shares as soon as trading opens.