Amid the merger activity involving some of the largest Massachusetts-based banks, the state has also seen some credit unions combine.

Greylock Federal Credit Union acquired the Credit Union of the Berkshires on Oct. 1, with the system conversion expected at the end of October, Greylock said in a statement last month. The two Pittsfield-based institutions had announced merger plans in May. Credit Union of the Berkshire’s members voted in favor of the deal in September.

“On behalf of CUB’s amazing staff and Board of Directors, I would like to extend a heartfelt thank you to all of our members,” CUB’s board president Beth Wallace said in a statement last month. “For 80 years, we have benefited from the patronage and support of our wonderful community. We are all very excited to be joining the Greylock family and look forward to seeing all our members there soon.”

Greylock is the largest credit union based in Western Massachusetts with about $1.49 billion in assets and nearly 93,000 members as of June 30. CUB had about $20.4 million in assets and 1,565 members as of Sept. 30, according to the National Credit Union Administration.

In its notice to members before the vote, CUB’s board of directors said without the merger, the credit union would need to make investments in people, technology, products and services to compete in the marketplace.

Greylock plans to close CUB’s only branch on Oct. 29, citing the proximity of a Greylock branch less than two miles away. CUB’s employees have been offered positions at Greylock. According to the NCUA, CUB had four full-time employees.

“Greylock is honored to be chosen to carry on CUB’s legacy of community and exceptional personal service,” Greylock’s board chair, Stanley Walczyk, said last month. “We are looking forward to meeting all of their members and learning from their wonderful staff. The credit union legacy is strong in Berkshire County and we are grateful to be able to support its continued growth.”

Another small credit union, Worcester-based St. Vincent Hospital Credit Union, was acquired in July by Shrewsbury-based Central One Federal Credit Union, which has about $701 million in assets. SVHCU had about $14.6 million in assets and more than 1,500 members. The branch at St. Vincent Hospital was retained, and the credit unions plan to complete the conversion in November, according to SVHCU’s website.

SHVCU said on its website that merging with another institution would increase operating efficiencies and enhance services, benefits, and convenience for members and the community.

Earlier this year, Chelsea-based Metro Credit Union completed its acquisition of Gloucester Municipal Credit Union, and members of another small credit union, Gloucester Fire Department Credit Union, are scheduled to vote today on a merger, also with Metro Credit Union.