Omnicare, the biggest institutional pharmacy provider in the long-term care sector, publicly announced a $715 million bid for top rival PharMerica on Tuesday. Dissatisfied with the outcome of behind-doors talks over the past four months, Omnicare leaders decided to take their case directly to PharMerica board members.

Omnicare’s bid of $15 per share represents a 37.2% premium over Monday’s closing price ($10.93), and a 25.9% premium over the average closing price for the month previously, according to the Omnicare announcement. PharMerica stock rose to nearly $15 early Tuesday morning but as of midday had dipped back below the $14 mark.

An Omnicare spokesman said Tuesday that PharMerica first approached Omnicare in mid-April about a potential acquisition. After Omnicare twice made purchase offers that were rebuffed, the company decided to go public with its second offer.

“Our strong preference is to work with PharMerica to negotiate a mutually acceptable transaction,” wrote Omnicare CEO John Figueroa in a letter to the PharMerica board. “However, if you continue to refuse to engage in meaningful negotiations, we are prepared to submit our proposal directly to your stockholders. We urge you to reconsider our proposal.”

The proposal is not subject to any financing contingencies and would include PharMerica’s net debt, Figueroa noted. Any potential deal, however, would be subject to regulatory approval, especially in light of the companies’ top positions in the drug delivery sector.

Speculation that PharMerica was seeking a buyer spread in industry circles in the spring. PharMerica acknowledged in late June that the Securities Exchange Commission had instigated an inquiry into unusual stock trading activity, no doubt sparked by sales speculation.

A PharMerica representative declined a McKnight’s request for comment Tuesday.