Nationwide has withdrawn shared equity mortgages for home movers, including applications which qualified under the Help to Buy shared equity loan scheme.
Nationwide will continue to lend to first-time buyers under the Help to Buy scheme.
The building society said this was a direct response to an earlier move by Halifax to withdraw the availabilty of homemover shared equity and shared ownership mortgages through intermediaries.
A spokeswoman said: "First-time buyers make up the majority of all shared equity demand and Nationwide and other lenders continue to participate in this market.
"Nationwide supports around one in five of all first-time buyer mortgages in the UK and we will continue to help those buyers to take their initial steps on the housing ladder."
Nationwide said the market for shared-equity mortgages for homemovers continued to served by a number of other lenders.