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That 5.7 percent market share in the U.S. ranks Wells Fargo eighth in overall revenue from investment banking, but its revenue from debt capital markets—issuance of bonds and loans—comes in third, besting peers Citigroup and Morgan Stanley.
The secret sauce may be a strong presence in securitized lending.
The bank has nabbed the No. 1 spot on asset-based lending, ousting Bank of America. A marquee 2013 deal: One such loan for J.C. Penney this spring as it was gasping for capital.
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Wells Fargo played coy about investment banking for years: Its earnings reports run into the dozens of pages, but investment banking takes up a matter of paragraphs.
And where rivals break down the dollar values of merger advisory, fixed income trading, equities and other Treasury businesses, Wells Fargo simply lumps it all as "Wholesale Banking."
When I asked one executive what lines of business in the investment bank were responsible for huge jumps in earnings, the person responded: "The normal stuff."
On Jan. 7, it placed a hardly coy full-page ad in the middle of The Wall Street Journal's Money and Investing section, touting its various big-ticket deals last year. (Bookrunning on bonds for Microsoft, Bally and the state of Illinois, for instance.)
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Some of that "stuff" is big indeed: A ticket to a spot on an $11.5 billion credit facility and $3.1 billion in bonds supporting the acquisition of H.J. Heinz by Berkshire Hathaway and 3G Capital.
It's been a choppy business—earnings in it aren't always up each quarter—but year over year, growth has steadily remained in the 30 percent range.
Investment banking has been a bright spot for a company that, as the nation's largest mortgage provider, could benefit from diversification as housing activity slows.
—By CNBC's Kayla Tausche. Follow her on Twitter