The acquisition that will make Berkshire Bank the largest state-chartered regional bank in Massachusetts is all but complete.

Berkshire Hills Bancorp, the holding company of the bank, yesterday announced that all regulatory approvals for the acquisition of Commerce Bank have been received, and that the deal is expected to be complete on Oct. 13.

The purchase will add $1.9 billion in assets, putting Berkshire up to about $11.5 billion in assets, crossing the $10 billion threshold that brings more regulatory scrutiny and costs under the Dodd-Frank Act. The deal will also give Berkshire an additional 16 branches, three in Boston and several in central Massachusetts.

The Commerce Bank name will be retained in all of the Worcester area branch locations, Berkshire Bank Spokesperson Heidi Higgins said in a statement. However, the Commerce branches in Boston will become Berkshire Bank locations as part of the systems integration in the first quarter of 2018.

The deal, announced in May, is valued at $209 million and will entitle Commerce shareholders 0.93 shares of Berkshire common stock for each share of Commerce common stock.  The exchange ratio is fixed and the transaction is expected to qualify as a tax-free exchange for shareholders of Commerce Bancshares Corp.

Commerce Bank will get two seats on Berkshire’s board of directors.

According to call report data, Berkshire has spent roughly $12.7 million on acquisition, conversion and restructuring-related expenses through the first six months of 2017.

This article has been updated to clarify that Berkshire will be the largest state-headquartered regional bank; State Street is the largest state-chartered bank by assets.