Five years ago today was when the market hit its intraday low of 666. Since then, the market has been on a bull run, defying the market bears who called for a pullback at every turn. But how long can it possibly continue?

On Monday's edition of Investor Beat, host Chris Hill and Motley Fool analysts Matt Argersinger and Taylor Muckerman look at a recent statement from hedge fund manager Seth Klarman. His long tenured track record of market outperformance lends a lot of weight to his words, so when he says the market is entering bubble territory, it could definitely mean that looking more carefully at valuation today before buying a stock could be a prudent decision.

Then, the guys look at four stocks making moves on the market today. FMC Corp was up today after the chemicals company announced that it's spinning off its health-care and agricultural divisions. McDonald's monthly same-store sales fell by 0.3%, which, despite being small, is the second straight month of falling comps for the fast-food giant. RetailMeNot lost big today as a new competitor in the daily-deals game emerged on the scene with the IPO of last week. And The McClatchy Company hit a five-year high on word that its joint venture may be putting up for sale.

And finally, Matt and Taylor each highlight one company they'll be watching closely this week. Taylor discusses eBay and the continuing battle with Carl Icahn over whether to spin off its PayPal business, as well as who should be on the company's board of directors, while Matt will be watching Biglari Holdings. The company owns a Midwest fast-casual restaurant chain called Steak 'n Shake, as well as 20% of Cracker Barrel, and has now purchased the men's magazine Maxim. Matt sees Sardar Biglari as a "go anywhere" investor, but will still be very curious about how he plans to make Maxim work in a portfolio of restaurant holdings.

Will investors run for the hills if today's "bubbles" start to pop?
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Chris Hill owns shares of eBay. Matthew Argersinger owns shares of Biglari Holdings and has options on eBay. Taylor Muckerman has no position in any stocks mentioned. The Motley Fool recommends and owns shares of eBay. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.