One of the fastest-growing areas in the country is the Southeast, and it seems appropriate that Southeast-based banks like Wachovia (NYSE:WB), Bank of America (NYSE:BAC), and SunTrust (NYSE:STI) have been some of the fastest-growing large banks over the last decade or two.

In SunTrust's case, we now have fourth-quarter results to digest. One word of note on the presentation -- SunTrust decided to offer up financial information as though the acquisition of NCF had been in place all year. Because the deal closed on Oct. 1, 2004, that really has no bearing on the results for the quarter, but investors should keep that in mind when perusing the annual results for themselves.

At the bottom line, the company reported that net income climbed 13% and earnings per share were up 12%. This growth was fueled by pretty strong net interest income growth of 10%, offset by more sluggish non-interest income growth of just 4%.

Looking at net interest income, we see that the net interest margin fell slightly to 3.1%. Interestingly, while SunTrust's margin held up a bit better than that of other banks, it's at a lower level than many banks' (more on this later).

For the balance sheet, we see that loans climbed 14% and total deposits were up almost 15%. Those sound like good numbers, but I think we should look deeper. What troubles me about the loans is that there was great growth in residential mortgages and commercial real estate, but commercial business and consumer loans were both pretty weak -- making SunTrust even more exposed to real estate (and, by extension, real estate prices).

On the deposit side, average consumer/commercial deposits were up just 5% and brokered deposits jumped almost 97%. That's not so good -- brokered deposits are generally a more expensive form of capital (versus core customer deposits), and that could be part of the reason that the net interest margin is relatively low. It could also be a regional competition issue, though, as neither Wachovia nor Bank of America have strikingly high net interest margins.

SunTrust has been a good grower and is still growing faster than its group as a whole. What's more, it has a very attractive franchise, and details like more than 300 branches in Wal-Mart (NYSE:WMT) stores and a big chunk of long-held Coca-Cola (NYSE:KO) don't hurt. Still, I'm a bit worried about the exposure to real estate and brokered deposits, and I think investors should carefully consider those issues before buying.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).