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 99 Cents Only Stores (NYSE: NDN) climbed 10% on Friday after The New York Post reported that Apollo Management was ready to make an offer on the discounter.

So what: The newspaper had suggested last month that an Apollo bid was possible, but this latest report has investors believing that a deal is now probable. If the paper’s unnamed source is to be believed, Apollo's looming offer of $22-$24 per share -- topping an earlier bid made by Leonard Green & Partners and the company's controlling Schiffer-Gold family -- represents about a 23% premium to yesterday's close.

Now what: Expect the bidding war to continue. The New York Post also reported that Leonard Green is thinking about a final bid that would be substantially higher than the current offer. So while long-term Fools know never to buy solely on takeover talk, speculative types might just have a short-term opportunity on their hands.

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