Wells Fargo grabbed a hefty 26.5 percent share of new Ginnie Mae mortgage securities issuance in 2004, leading a pack of five heavyweights that dominated a shrinking business line. Wells Fargo issued $33.54 billion of Ginnie MBS last year. Although that raised the company’s share of the Ginnie market several points from the 22.2 percent share it had for all of 2003, Wells Fargo’s issuance volume was down 31.4 percent for the year. …