Citi analyst Tyler Radke downgraded Palantir Technologies (PLTR) to Sell from Neutral with a price target of $15, up from $10.

After a 150% rise in the stock since the September direct listing, the stock is "vulnerable" heading into 2021 with the upcoming lockup expiry, and an expected deceleration in growth, Radke tells investors in a research note.

The analyst sees risk around the lapping of COVID-19 related contracts, which he says have the potential to become headwinds in the second half of 2021 and into 2022. He's also more skeptical on the Palantir "bull case" in the commercial business, where he says there is optimism that the company's simplified new products can drive an inflection in customer growth.

Radke sees high levels of competition and the lack of investment by Palantir in the "right areas" limiting its success.