Palantir and BigBear.ai have gone in opposite directions since their market debuts. Palantir, which opened at $10 on its first day, now trades at nearly $120. BigBear.ai, which opened at $9.84 after its SPAC merger, now trades at about $9. Let's see why the bigger AI company outperformed the underdog, and if it's still the better investment now.

Related: Walmart, Booking.com will rock markets in a busy earnings week But there was probably more behind the selling, including that Palantir's shares had become way too pricey and were vulnerable to a selloff.

Palantir's valuation is retreating today after Walmart issued sales guidance for this year that spooked Wall Street. On the heels of a 5.6% increase for its annual revenue last year, the retail giant only expects sales growth to be between 3% and 4% this year.