Smaller stocks are winning again, but for how long?

The stock market’s biggest gains are once again coming from its smallest companies, but the trend may not last much longer.

Smaller-company stocks like Allegiant Travel and AK Steel have been soaring since late December and leading the rest of the market, a sharp reversal from much of the winter, when smaller stocks were plunging more than the rest of the market.

The Russell 2000 index of small-cap stocks has jumped 19.8 percent since Christmas Eve versus 16.2 percent for the big stocks in the S&P 500 large-cap index, though neither has returned to the records they set late last year.

Bed Bath and Beyond, for example, has surged 46.3 percent since Christmas Eve, helped by a stronger-than-expected earnings report where it said it’s ahead of plan in eventually returning to profit growth. Besides earnings reports, smaller stocks have also been benefiting in recent weeks from reduced worries that the Federal Reserve will raise interest rates too quickly.