Palantir's stock is rallying after another excellent quarter. The company's sales hit $1 billion in the second quarter and profits more than doubled. Its valuation has eclipsed that of many blue-chip stocks.

The stock has climbed 2.5x since early January and now trades at around $185 per share. After such a rapid ascent, should investors holding sizable gains cash out?

Palantir’s score on that measure is 94: higher than any other enterprise-software firm with equivalent or greater sales. Among the world’s 25 biggest companies by market value—of which Palantir is one—only Nvidia,