Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of banking giant Citigroup (NYSE: C) found some serious buyers today, and the stock jumped as much as 11% in intraday trading on heavy volume.

So what: Today, Citigroup announced that it hired Kathryn Dinkin away from Wells Fargo (NYSE: WFC) to head its East region consumer banking segment. What, you're not convinced that this is enough to send shares spiking?

OK, the real reason that Citi's shares are soaring today is the banking industry's huge news: Berkshire Hathaway's (NYSE: BRK-A) (NYSE: BRK-B) $5 billion investment in much-maligned Bank of America (NYSE: BAC). While Citi doesn't get a penny of this investment, it's benefitting from the afterglow of the confidence boost that came from Warren Buffett's apparent belief in the post-financial-meltdown banking system.

Now what: By tomorrow, everyone will have forgotten about Buffett's B of A investment. That may be a bit of an exaggeration, but the stock market has an extreme "what have you done for me lately" attitude and an event like this is unlikely to have a long-lasting effect. That's not to mention the fact that everything is going to be overshadowed tomorrow by what Federal Reserve Chairman Ben Bernanke does or doesn't say in his speech in Jackson Hole, Wyo.

Is it significant that Warren Buffett invested in Bank of America? I think Buffett's a sharp investor, so I'd say "yes." But is this a good reason to rush to buy Citigroup stock? Nope, you better have some better reasons on your list.

Want to keep up to date on these stocks?

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.