Omnicare is a specialty pharmacy providing drugs for chronic conditions.

The US mega drugstore operator CVS Health Corp, on Thursday, said that it will buy the United States top pharmacy services provider, Omnicare Inc for $10 billion to gain a market share of the senior patients market.

The offer by CVS at $98 per Omnicare share amounts to a 4 percent premium over Wednesday’s closing price, roughly a 21 percent premium over 21st April’s closing price of Omnicare.

The deal values Omnicare at around $12.7 billion, including $2.3 billion in debt, according to the companies.

“Both (CVS and Omnicare) are big part D players and there could be some scale benefits in negotiating with other payors,” noted Cowen & Co analyst Charles, on Wednesday.

CVS estimates that the deal will add 20 percent per share to the companies adjusted earnings in 2016, with the deal helping to expand its presence in the fast moving specialty pharmacy business of costly drugs for complex or rare clinical conditions. It also said that Barclays will be financing $13 billion of the deal with it tentatively closing in the end of 2015.

Baby Boomers, the larger than expected generation in the US, born shortly after World War II, reportedly comprises the group of highest-cost medication users. Baby Boomers requiring medication due to two or more chronic conditions increased by 39.2 percent in the last decade, according to the latest report from the Centers for Disease Control and Prevention.

Omnicare’s shares touched $95.75 in premarket trading while CVS’ peaked at 104.81 on Thursday.