Federal Reserve Board chairman Alan Greenspan said on Saturday the flurry of bank mergers had heightened his objections to letting banks shift operations from holding companies under the Feds oversight. This is a terribly crucial issue, especially now that we are looking at apparently an increased size in merged banking institutions, because a very large bank requires a very subtle handling in the event of a crisis. A very, very large bank requires even more, Greenspan told a banking group meeting. Greenspan repeated his concerns about proposals to let banks move into new lines of business without restructuring as holding companies.