NEW YORK (CNN/Money) - Two brokerage houses issued positive notes on Symantec, while Cinergy and Linear Technology also got a boost before the opening bell Thursday.

In a morning note, Merrill Lynch increased its investment rating on Symantec (SYMC: Research, Estimates) to "neutral" from "sell" and raised its profit estimates a day after the company beat Wall Street estimates and guided higher. Credit Suisse First Boston also increased its 2003 earnings estimate for the company to $1.91 a share from $1.80 and raised its price target to $56 a share from $49. Shares of Symantec fell $1.29 to $46.05 Wednesday.

Credit Suisse also raised its 2003-2006 profit estimates for Genentech (DNA: Research, Estimates) a day after the biotech company provided positive guidance. Shares of Genentech fell $1.21 to $35.21 Wednesday.

Merrill Lynch raised its 2002 earnings estimate to $2.60 a share from $2.50 and its 2003 estimate to $2.65 a share from $2.50 for Cinergy (CIN: Research, Estimates). The firm also increased its price target on the diversified energy company to $38 a share from $34 following a positive analyst meeting and dividend increase. Shares of Cinergy fell 43 cents to $34.07 Wednesday.

Merrill also increased its 2003 profit estimate for circuit maker Linear Technology (LLTC: Research, Estimates) to 72 cents a share from 69 cents and raised its 2004 forecast to 89 cents a share from 84 cents after the company reported better-than-expected results Tuesday night. Shares of Linear fell $1.45 to $29.35 Wednesday.

J.P. Morgan started coverage of Diamond Offshore Drilling (DO: Research, Estimates) with an "overweight" rating saying "improvement in the deepwater market provides meaningful earnings upside."

UBS Warburg increased its investment rating on the global and European pharmaceutical sectors to "neutral" from "underweight," saying it sees a combined Pfizer (PFE: Research, Estimates) and Pharmacia (PHA: Research, Estimates) as the dominant global player.

Lehman Brothers cut its rating on Sun Communities (SUI: Research, Estimates) to "underweight" from "equal weight" and downgraded Manufactured Home Communities (MHC: Research, Estimates) to "equal weight" from "overweight," citing an uncertain home sales market.  

--from staff and wire reports