Zhitong Financial APP learned that according to media reportsMerck & Co Inc (MRK.US)The acquisition is about to be completedAcceleron Pharma (XLRN.US)The deal is likely to be announced this week.

It will be the largest deal in Merck & Co Inc's history and shows the company's support for its rare disease business.

Acceleron's share price has soared more than 37 per cent since September 16, valuing it at just under $11 billion. Merck & Co Inc has a market capitalization of just over $186 billion, and according to the latest report, the company has $8.6 billion in cash and $24 billion in long-term debt.

Acceleron's share price rose on Friday amid reports that it was in talks about a takeover.

As of press time, Acceleron was up 6.69% in Monday trading and 0.77% at $180.25 in after-hours trading. Merck & Co Inc rose 0.16% to $73.50 in after-hours trading.