Raise your hand if you think Mellon Financial (NYSE:MEL) is a bank. If you raised your hand, you're wrong. But don't feel bad -- that seems to be a common misconception. What Mellon actually does is a little further below many investors' radar -- asset management, trust and custody services, and treasury services are the name of the game here.

Fourth-quarter results were solid, albeit not spectacular. Income from continuing operations was up a not-so-whopping 4.5%, while fee-based and other non-interest revenue climbed 13%. Net interest revenue rose about 4% on a fully taxed equivalent basis but constitutes a much smaller part of the top-line figure -- $126 million versus $1.1 billion in non-interest revenue.

Fee revenue from asset management rose about 15% with the large mutual fund business, showing 10% growth and the institutional client business growing about 17%. Along the way, assets under management rose 11% to $781 billion. On the trust and custody side, fee revenue was up 31%, while assets under administration rose 21% to $3.91 trillion (yes, that's trillion).

By most standards, this is a solid business. The company sports a return on equity of about 20% and is one of the largest institutional money managers behind the likes of State Street (NYSE:STT) and Barclays (NYSE:BCS). It's also a big player in custody services, though not quite as large as the likes of State Street, Citigroup (NYSE:C), Motley Fool Income Investor pick JPMorgan Chase (NYSE:JPM), or Bank of New York (NYSE:BK). Likewise, it's not as big in private wealth management as Citigroup or Merrill Lynch (NYSE:MER), though it still has a sizable franchise.

Asset management and custodial services are very different businesses, and that can make valuation a little more challenging if you're a fan of relative or comparative valuation. It has also led to calls for the company to split the business -- something management has thus far rejected. In any case, while I like the unsexy yet lucrative markets that Mellon serves, I just don't see the stock as a compelling bargain today.

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Fool contributor Stephen Simpson owns shares of JPMorgan Chase but has no financial interest in any other stocks mentioned (that means he's neither long nor short the shares). The Motley Fool has a disclosure policy.