How do you get $2.5 billion? I get about $1 billion. BK owns 20.7% (Source 2012 annual report financial section page 128). Bloomberg estimates a value of $5 billion (current market value after Monday's gain is $4.6 billion). It would have to go to $12.5 billion for us to get 2.5 billion. At $1 billion it would be a $550 pre-tax gain.
From WSJ: "Bank of New York Mellon Corp. has agreed to sell its stake in Hong Kong-based Wing Hang Bank Ltd., a move that will result in a gain of about $500 million for the New York-based trust bank.
The bank is selling its stake, which it says had a book value of $544 million at the end of March, to Oversea-Chinese Banking Corporation Ltd., or OCBC."