A bidding war is a good thing for shareholders, right? Not necessarily for shareholders of Pivotal (NASDAQ:PVTL), which for whatever reason seems determined to take the low-bid offer.

In light of the challenging market for customer relationship management software (CRM), Pivotal retained RBC Dain Rauscher to shop itself to buyers in April. By October 8, a deal was struck, in which the private-equity firm, Oak Investment Partners, agreed to pay $1.78 per share in cash for the company. Moreover, Oak would then merge one of its portfolio companies, Talisma, into Pivotal.

A week before the shareholder vote, though, Onyx made an unsolicited offer to buy Pivotal at an exchange ratio of 0.475 Onyx shares for each Pivotal share, which at the time translated into a purchase price of $2.25 per Pivotal share. The combined entity would have had revenues of $110 million, catapulting the firm into the No. 2 spot among pure-play CRM companies. Of course, Siebel Systems (NASDAQ:SEBL) would have remained the clear No. 1.

However, Pivotal's board rejected the offer. In fact, Pivotal's response was, well, tantamount to recommending that investors short Onyx. In a press release, Pivotal called Onyx a "distressed company facing a very uncertain future." (Then again, Pivotal should understand, as its financial situation is similar.)

Not to be outdone, this week the software unit of Chinadotcom (NASDAQ:CHINA) made an unsolicited bid for Pivotal. The bid came with an option: Pivotal shareholders could take $2 in cash or $1 in cash plus $1.14 in Chinadotcom stock.

Yet again, Pivotal's board swiftly rejected the offer. While the board didn't criticize Chinadotcom's business as it had Onyx's, it instead focused on the "conditional" nature of the offer, even though the bid looked similar to Oak's. Chinadotcom had been willing to provide a bridge loan of $20 million to facilitate a deal -- which, in corporate finance, isn't a telltale sign of conditionality.

What's going on here? It looks like Oak wants to save Talisma, one of its venture deals. Plus, in transactions to take a company private, it's tempting to try to take out the public shareholders at a low-ball price. Management and the board stay in place. They can slash costs and suck out cash or position the company for a bigger deal, reaping a nice return down the road.

Pivotal shareholders will vote on the Oak bid on Friday. So far, the bid is still at $1.78. (Yesterday, Pivotal's stock price closed at $1.95.) It's not clear why shareholders would vote for a price lower than that offered by the public markets. In this drama, though, anything is possible.

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Tom Taulli is the author of six books on investing and finance, such as the Complete M&A Handbook (Random House). You can reach him at tom@taulli.com.