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 baby clothier Carter's (NYSE: CRI) are up more than 14% as of this writing thanks to a strategic investment from Boston private equity firm Berkshire Partners LLC.

So what: Berkshire disclosed in a Securities and Exchange Commission filing a series of investments that amount to a 13% stake in the company. In no other publicly traded position does Berkshire control even 10% of the shares outstanding, though its 9.4% stake in TransDigm Group (NYSE: TDG) comes close.

Now what: Fools tend to like Carter's, granting the stock a four-star rating in CAPS, while my colleagues at Motley Fool Hidden Gems like TransDigm. Is there enough commonality here to make Carter's a verifiable diamond in the rough? Berkshire seems to think so, but the stock isn't cheap trading for 17 times earnings. Tread carefully if you choose to invest.

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