Oil Dips Below $72 a Barrel

Meanwhile, energy stocks were hammered in Thursday's trading session. The CBOE Oil Indexslid 2.6% to 724.41. ConocoPhillips (COP Quote) lost 2.6% of its value, closing at $78.57. Exxon Mobil(XOM Quote) fell 3.1% to $84.79.

Among ratings changes, Lehman Brothers upgraded Marathon Oil (MRO Quote) to overweight from equal weight. However, shares of Marathon dropped 4.2% to $49.86.

Kinder Morgan Energy Partners (KMP Quote) was upgraded by Sanders Morris Harris to buy from neutral. The stock is down 2.7% at $49.74.

Transocean (RIG Quote) was upgraded by Matrix Research to strong buy from buy. Shares fell 2.1% to $101.42.

Chesapeake Energy (CHK Quote) was downgraded by Wachovia to market perform from outperform, lowering its shares 3.9% to $34.06.