Ronald A. Walter , executive vice president and head of the pension...

Ronald A. Walter, executive vice president and head of the pension group at Citigroup Investments Inc., New York, is retiring at the end of the month, according to sources familiar with Mr. Walter. Mr. Walter and Citigroup spokeswoman Shannon Bell declined to comment. Information about Mr. Walter's replacement could not be learned by press time. Citigroup has $8.6 billion in defined benefit assets and $9.9 billion in defined contribution assets.