You know what the trouble is in writing about stocks as opposed to politics, movies, or celebrity goings-on? You actually have a track record, and the line between right and wrong isn't usually anything other than crystal clear. So it is with a wince that I point out that the stock of electronic financial transaction processor Global Payments (NYSE:GPN) has gone up another 10% from where I pronounced it "fully valued" back in December.

In my own half-hearted defense, I never questioned the growth potential of the story, and the company delivered more of that in its third quarter. Revenue in the quarter grew another 15%, and operating margins expanded by nearly two full points. When it was all said and done, earnings per share were up 33% and the company boosted its guidance for the full year.

There was also an item in a recent 8-K filing that bears mention. The company chose to cut off what it called a "suspicious" merchant because of its role with what apparently was a fraudulent company. Now, Global Payments has established a cash reserve account for dealing with transactions with this merchant, and it looks like that reserve will be adequate for dealing with charge-backs related to the fraudulent company. So, all in all, it probably won't have any meaningful impact on Global Payments.

In the meantime, things that do matter -- like the company's growing money transfer business, domestic merchant processing operations, and future Asian business through HSBC (NYSE:HBC) -- all seem to be on track. So while there's always going to be the threat that rivals like First Data (NYSE:FDC) and Bank of America (NYSE:BAC) could cause trouble for Global Payments, that doesn't seem to be happening at this point.

When it comes to the stock, though, I'm not as sanguine. First Data and Bank of America both look like more appealing options today (though only a small part of BoA's business is directly relevant to Global Payments or First Data). Then again, there's no rule that I know of that says the expensive stock of a fast-growing company can't get even more expensive . at least in the short run.

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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).