Meridian Interstate Bancorp Inc., the holding company for East Boston Savings Bank, has sold its 40 percent stake in Hampshire First Bank, after Hampshire’s planned merger with New York-based NBT Bank NA.

Meridian agreed Friday to vote its 1.2 million shares of Hampshire First in favor of the merger with NBT. Meridian also holds 60,000 Hampshire stock warrants. As of Sept. 30, Hampshire First common stock was worth $10.52 per share.  The warrants held an exercise price of $10 per warrant.

Hampshire First was started by Meridian in 2006.

Under the terms of the deal, 65 percent of outstanding Hampshire First common stock will be converted into the right to receive 0.7 share of NBT common stock. The remaining 35 percent of outstanding shares of Hampshire First will be sold for $15 cash.

The exchange ratio is based on NBT’s closing stock price of $21.37 per share as of Nov. 10.

Norwich, N.Y.-based NBT has 128 branches in four states: New York, Pennsylvania, Vermont and Massachusetts.

Manchester, N.H.-based Hampshire First has five branches in southern New Hampshire.

Richard Gavegnano, president and CEO of East Boston Savings Bank, told Banker & Tradesman Hampshire First grew to about $273 million in assets after its founding in 2006, but it would now require additional capital investment to grow the bank further.