Shares of ride-hailing giant Uber (UBER) touched record lows on Wednesday as the lockup period on the company's shares held by early investors and employees expired, opening the window for insiders to sell their shares. 

Shares of Uber were down 4.18% on Wednesday to $26.85 after tumbling nearly 7% earlier in the session to a low of $25.58. The stock fell almost 10% on Monday after Uber posted mixed third-quarter results. It also fell on Tuesday, hitting a record low, despite U.S. stock indexes hitting fresh highs.

Indeed, with this week's losses, the ride-hailing and food-delivery-ordering stock has fallen 38% from its $45 initial public offering price. With Wednesday's lockup expiration, an additional 84% of the company's current fully diluted share count comes onto the market.

That translates into some 763 million additional shares, or $20 billion of Uber stock, hitting the market, Wedbush analyst Daniel Ives estimated in a recent research report.

The lockup expiration could "cause an avalanche of selling as early investors and insiders hit the bid, which remains a major Street worry around near-term pressure," Ives wrote.

To be sure, different stocks react differently to expired lockup periods. Beyond Meat (BYND) shares plunged nearly 20% after its lockup expired at the end of October. On the flip side, and somewhat more comparable, shares of Uber rival Lyft (LYFT) also fell after it announced an earlier-than-expected lockup expiration in mid-August, though not as dramatically.