What happened

Shares of Unisys Corp. (NYSE:UIS) rose on Wednesday after the IT company was included in a major small-cap stock index. As of 12:15 p.m. EDT, the stock was up about 10.3%.

So what

S&P Dow Jones Indices announced on Tuesday that Unisys will be added to the S&P SmallCap 600 index, effective prior to the opening bell on Sept. 4. The stock will replace Marriott Vacations Worldwide, which is moving into the S&P MidCap 400 index.

Orange-and-blue stock chart showing a rising line

Image source: Getty Images.

Shares of Unisys have more than doubled this year, including Wednesday's surge, pushing the company's market capitalization above $900 million. The inclusion in the small-cap index will require funds that track that index to buy and hold shares, which could further boost the stock (at least in the short run).

Now what

This index-related rally comes less than a month after shares of Unisys soared following the company's second-quarter report. Unisys easily beat analyst estimates, although revenue was down adjusting for currency.

Unisys has rewarded investors this year, and it will be more broadly owned now that it's part of the small-cap index. But the company will need to keep beating expectations to keep the rally going.