Sugarbush president Win Smith will remain in that role and will oversee daily operations and plans for future capital improvements.
"Having been a family-owned resort for nearly two decades, we were keen to find the right next owner of Sugarbush Resort," Smith said in a statement. He added that Alterra "will continue to maintain our culture, values and commitment to our community" in addition to the planned investments.
Officials say the sale is expected to close in the first quarter of 2020.
Terms of the transaction have not been disclosed.
Among the Alterra Resorts are Steamboat and Winter Park in Colorado; Tremblant in Quebec; and Deer Valley Resort and Solitude Mountain Resort in Utah.