Caremark ( CMX) shareholders don't seem to be on board with management's less-is-more message.

The Nashville, Tenn., mail order pharmacy formally rejected an unsolicited $26 billion cash-and-stock takeover bid from rival Express Scripts ( ESRX) late Sunday. Caremark said shareholders will fare better under a $21 billion all-stock merger with CVS ( CVS), the giant retail pharmacy chain.

Caremark portrays Express Scripts as a jealous suitor that, desperate to derail the CVS deal, has promised more than it can deliver. Caremark claims Express Scripts could stir up "significant, if not insurmountable," antitrust issues if it keeps trying to get its way.

It's no surprise that Express Scripts rejects those criticisms. But increasingly, it's not alone.

Some critics have started to question Caremark's motives. They say recent regulatory filings show Caremark leaders will make out much better than shareholders in the CVS deal. And they note that Caremark was facing challenges on many fronts long before the merger was announced.

"Express Scripts put together this fantastic presentation, justifying why Caremark should do the merger with them," says Massachusetts investment strategist Peter Cohan, who has no financial stake in any of the companies. "This Express Scripts offer looks clearly better for shareholders. So I'm wondering: Why is Caremark just kind of blowing them off?"

Investors wondered the same thing Monday, sending Caremark down 2% and both of its suitors down fractionally.

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