Many investors are losing money in today's market, but at least one appears to be minting it. William Ackman's well-timed bet on Longs Drug Stores (NYSE: LDG) may have netted him several hundred million in mere weeks, but the famous activist is now questioning whether it deserves more. Pershing Square, which he manages, threatened to vote against the deal amid concerns that CVS may not be paying full price for Long's real estate assets.

Real estate is the crown jewel in CVS' deal to acquire Long's. Newly public reports show that CVS put a "conservative" value of $1 billion on 200 Long's retail stores, three distribution centers, and three office buildings. Further, CVS noted that it intends to make money off the assets by either selling them or generating cash through sale-leaseback transactions. Several investors have threatened to vote against the merger by refusing to tender their shares.

The real estate story may also explain why Ackman was interested in the first place. One of the activist investors favorite strategies is to push for value to be unlocked through the same transactions mentioned by CVS above. Target, for example, is one company he owns where he sees the real estate as being worth as much as the entire company if not more. Now that CVS has beat him to the punch, he and other investors are likely to put up a fight.

Arbitrage investors - those that bet on takeovers - have already begun to bet that CVS will increase its bid as shares are trading above the takeover premium. The other options are the CVS will extend the timetable of its tender offer or walk away from the deal altogether. The law firm behind the complaint, BLB&G, has a history with CVS too. The law firm helped force the chain to pay an additional $7.50 per share in its acquisition of Caremark in 2006.