Sue Noffke, Schroders' head of UK equities, told The Times the terms of Avast's sale to NortonLifeLock "materially undervalue" the London-listed group.
Last week, NortonLifeLock agreed to buy its UK rival Avast for up to $8.6 billion in cash and shares to create a leader in consumer security software.
($1 = 0.7272 pounds)
(Reporting by Kanishka Singh in Bengaluru; Editing by Chris Reese)