Roche Holding AG began a tender offer to acquire all outstanding shares of Foundation Medicine Inc. for $137 per share in cash.

In June, the Swiss pharmaceutical company said it was going to acquire all the remaining shares of Foundation Medicine that it does not already own. The total transaction value of the merger is $2.4 billion on a fully diluted basis, valuing the U.S. genomic profiling company at $5.3 billion.

The tender offer will expire at midnight Eastern Time on July 30.

Following completion of the tender offer, Roche will acquire all remaining shares at $137 apiece through a second step merger as it continues to build on its personalized medicine offering for patients with cancer.

The closing of the transaction is expected to take place in the second half of 2018.

Roche first struck an alliance with Foundation Medicine in 2015 by acquiring a controlling 56.3% stake for $50 a share to improve the design and outcome of clinical trials. In April, the companies entered a collaboration to launch diagnostic tests for cancer in China.

Citi is acting as Roche's financial adviser, while Davis Polk & Wardwell LLP is serving as legal counsel to the drugmaker.

Goldman Sachs & Co. LLC is the Foundation Medicine Special Committee's financial adviser, while Goodwin Procter LLP is serving as legal counsel to the group.