A lockup provision that limited the ability of Palantir Technologies (PLTR -1.56%) insiders to sell shares expired last week, and as expected, some in the company are taking advantage.

Company co-founder Stephen Cohen sold 3.8 million shares over several transactions, according to regulatory filings, while general counsel Matt Long sold 469,000 shares and chief legal and business officer Ryan Taylor sold 190,991 shares.

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Palantir went public in late September via a direct listing, and the stock has soared more than 175% in the months since. As part of the listing, insiders were initially allowed to sell 20% of their shares, with the remainder not eligible for sale until now.

Some sales were expected following the expiration. Last week, company co-founder and chairman Peter Thiel disclosed the sale of 20 million shares through a trading plan, and Soros Fund Management said in November it would sell down its 18 million shares after the fund said it "does not approve of Palantir's business."

Insider sales are common, especially among executives who count company stock as a large piece of their net worth. But the sales are adding to the pressure on Palantir on what is already shaping up as a tough day for growth stocks, with the shares off 6% on Tuesday morning pre-market trading.

While the stock sales likely do not indicate insiders are souring on Palantir's prospects, it does add to the number of shares available for trade and can at least temporarily put a damper on price appreciation. Given Palantir's impressive surge higher, the case can be made the stock had gotten ahead of itself even without the added dynamic of insider selling.