Mark Spitznagel made a fortune predicting the "black swan" that hit markets last year. Now the relatively unknown hedge-fund manager is emerging from the shadow of his collaborator, Nassim Nicholas Taleb, with a big bet inflation will soar.

The 38-year old Mr. Spitznagel managed the Black Swan funds to triple digit returns last year with a bet on volatility. The returns have brought a flood of cash, sending assets for his firm, Universa Investments LP, rising to $6 billion from $300 million.

But,...