The Daily Telegraph says the firm’s advisers, which include Nomura and UBS, are believed to have worked on the document amid speculation about which insurance company is next on Clive Cowdery’s list of targets.
Resolution raised £600m from investors when it floated on the London Stock Exchange last year.
The firm agreed a deal to buy Friends Provident for £1.86bn in August.
Resolution is understood to be considering a move for Lloyds Banking Group’s life businesses Clerical Medical or Scottish Widows although it is also known to be interested in L&G.
The newspaper quotes a senior banker as saying the defence document was a “natural response” that any company in L&G’s position would draft in the current environment.
L&G chief executive Tim Breedon recently insisted the firm would not benefit from industry consolidation adding that it planned to grow organically.