Investors trying to get in on the Jamba Juice craze that's sweeping Wall Street these days could wind up pureed if they're not careful. Shares of Services Acquisition Corp. International ( SVI) are up 40% to $10.45 since last week's announcement that the so-called blank-check company plans to acquire Jamba, a national chain of smoothie stores, in a deal valued at $358 million. The acquisition is being hailed by some as proof that the blank-check IPOs recently flooding the market can pay off big for investors. Over the past three years, hedge funds and other investors have sunk more than $2 billion into 47 initial public offerings by blank-check companies -- fledgling businesses looking to raise money simply to acquire other businesses. But to date, only a handful of those blank-check companies have completed a merger with an actual business, and that includes the proposed Jamba Juice merger. Services Acquisition's deal is the most high-profile blank-check merger in the works. For Jamba, a 15-year-old company with 532 stores in 26 states, it's an opportunity to raise the cash necessary to compete with other national specialty food chains, such as Starbucks ( SBUX). But the ones most likely to score big on the deal are the well-connected corporate insiders who cobbled together Services Acquisition. Other big winners are the hedge funds that invested in the blank check's $127 million initial public offering last July -- and a subsequent private placement that will raise an additional $231 million to finance the merger. Technically, the Jamba takeover is a reverse merger, because it's one in which a private company -- Jamba -- goes public by merging with a publicly traded shell: Services Acquisition. However, investors currently buying up shares of Services Acquisition in the hope of getting in on the ground floor of a national chain face the risk of getting squeezed once the deal is completed.