That was fast: On their second day of trading yesterday, shares in Lyft fell 12 percent, to $69.01, below their I.P.O. price. That darkens the outlook for the ride-hailing company, and for other tech unicorns planning to go public. Lyft crashed below its I.P.O. price quickly. Other tech companies with big losses, like Groupon, Twitter and Snap, have suffered the same fate, but it took a while — almost two weeks, for Groupon. Investors may be worried about Lyft’s losses. The company lost nearly $1 billion last year.