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 Bank of Ireland (NYSE: IRE) were soaring today, gaining as much as 40% in intraday trading on heavy volume.

So what: Just as it seemed Ireland was about to take control of its last major private lender, a group of private investors stepped up to see that that won't happen -- at least for now. A $1.6 billion investment from an unidentified group of investors ensures that after the government underwrites a B of I rights issue, its maximum ownership stake would be 32%.

Now what: This certainly looks like a big vote of confidence in Ireland and its ability to navigate its fiscal and banking crisis. Fellow Irish banking giant Allied Irish Banks (NYSE: AIB) rose significantly on the news despite it just reporting that it will likely see losses through 2013.

For investors on the sidelines wondering what to make of this, my advice would be to make sure you have done your homework before jumping in here. While this investment may very well be a positive sign, we have little idea exactly why this group of investors is taking this plunge. For all we know, it could be a big heap of dumb money being thrown at what's still a dodgy situation.

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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 Facebook. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.