Wall Street was mixed at midday on Thursday. The Nasdaq Composite was 0.1 percent higher to 2,254.27, but the S&P 500 was 0.1 percent lower to 1,324.36 and the Dow Jones Industrial Average had dropped 0.2 percent to 11,592.38. The declines for the Dow and the S&P still left them near all-time and 5-year highs respectively.

An announcement from Wal-Mart that it will sell 30-day supplies of generic drugs for $4 in a trial program sent shares in drug retailers lower. Walgreen dropped 6 percent to $46.97, while CVS fell 9.2 percent to $32.18. The news also sent pharmacy benefit managers, the administrators for corporate and insurance prescription drug plans, lower. Medco Health Solutions dropped 3.4 percent to $60.75, while Caremark Rx was 4.3 percent lower to $56.56.

Carnival, the cruise ship operator, added 4.6 percent to $45.58 on better than expected third quarter earnings, mainly due to declining fuel costs.

Oil stocks were up as crude oil prices rose. BJ Services was 2.6 percent higher to $29.93, while Consol Energy added 5.9 percent to $30.78.

Food manufacturers saw gains on the strength of positive quarterly results. ConAgra, which makes Hebrew National hotdogs among other products, was 3.4 percent higher to $24.04, while breakfast cereal maker General Mills gained 3.7 percent to $54.97.

Wall Street was down at mid-session on Thursday as profit-taking and renewed worries about higher interest rates took their toll after new data showed that existing home sales in the US were up 5.2 percent in February. Higher crude oil prices also hurt buyer sentiment.

By midday, the Dow Jones Industrial Average had dropped 0.4 percent to 11,272.93, the Nasdaq Composite was down 0.3 percent to 2,296.35, and the S&P 500 was also 0.3 percent lower to 1,301.03.

Oil companies were higher on higher crude prices as well as on upgrades within the sector from Prudential Equity Group. Marathon Oil gained 1.6 percent to $77.49 and ConocoPhillips added 1.9 percent to $61.65.

Computer related sectors were mixed. Software maker Adobe Systems lost 2.6 percent to $35.66 after it said that earnings this quarter will be below predictions. Computer maker Dell added 0.2 percent to $30.46 on the news that it will purchase Alienware, which makes gaming computers. That news helped chip maker Advanced Micro Devices to gain 3.6 percent to $35.62. Search engine Yahoo was up 3.1 percent to $42 on positive comments from UBS.

General Motors added 0.8 percent to $22.19 after the majority stake in its financing arm was purchased by an investor group.

In the foods sector, General Mills gained 0.5 percent to $50.21 on a 7 percent rise in profits in the third quarter. ConAgra added 1.1 percent to $20.48 even though it announced losses in its third quarter due to one-time restructuring and legal costs.