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 Irish financial giant Bank of Ireland (NYSE: IRE) slipped today, losing as much as 11% in intraday trading on heavier-than-average volume.

So what: Following the results of the most recent round of banking stress tests in Ireland and the announcement of the country's plan for the banking industry, both B of I and Allied Irish Banks (NYSE: AIB) got a huge boost from investors. So why the apparent change of heart? Part of it is likely short-term speculators who are taking their gains and calling it a day. At the same time, longer-term investors may be questioning what the government's continued involvement in these banks will mean for equity shareholders.

Now what: On Friday, my fellow Fool Zeeshan Siddique suggested that the stress tests may have shown that nationalizing the entire banking sector is the way to go. That would obviously be terrible news for shareholders since -- at least under a full nationalization -- they'd be left with bubkes. While that might not be a particularly surprising outcome for Allied Irish, it would be more surprising to see it happen to the healthier B of I. But of course, we're not talking about straight economics or finance here -- we're talking politics. With the future of these stocks largely riding on the decisions made by the Irish government, I'd be nervous putting any money at risk except as a high-beta gamble.

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Fool contributor Matt Koppenheffer does not have a financial interest in any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool’s disclosure policy prefers dividends over a sharp stick in the eye.