The Monday blues have the potential to leave anyone feeling sluggish, and these companies today are no exception. Here is a look at some of Monday's worst performing stocks, stuck in a rut.

Shares of the mass media and entertainment company Discovery Communications (DISCA) - Get Report  got hammered during trading on Monday,closing lower down over 8%, after it reached an agreement with Scripps Networks Interactive Inc. (SNI) to buy the owner of HGTV, DIY Network and Food Network for $90 a share.

Plunging over 13.5% was biotech company Clovis Oncology (CLVS) - Get Report after announcing a clinical collaboration agreement with Bristol-Myers Squibb (BMY) - Get Report . The collaboration lessens the likelihood Clovis is targeted as a potential takeover.

"The deal may be modestly negative to investors eager to see Clovis get acquired, but the company retains full rights to Rubraca and to our eyes this more cautious deal probably reflects the new reality in IO," Stifel analyst Thomas Shrader noted.

Also getting crushed on Monday was Hertz Global Holdings Inc. (HTZ) - Get Report whose shares are lower over 19% after Barclays downgraded the stock amid concerns with used car values and weak rental car pricing. Barclays said the combination of company-specific and industry-wide issues have created the " perfect storm" for Hertz.

Closing lower over 2.7% is cigarette-maker Altria Group Inc. after the FDA announced plans to reduce the amount of nicotine in tobacco products to curb the number of tobacco-related deaths and illnesses in the U.S.

Falling over 5% is Pandora Media Inc. (P) whose shares took a hit as the music streaming giant announced it was shutting down its operations in Australia & New Zealand on Monday. The move provides further credence that the company continues to struggle financially.

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