NEW YORK (CNN/Money) - Merrill Lynch weighed in on several companies early Friday, downgrading publisher R.R. Donnelley, oil producer Amerada Hess and medical device maker Cerus, while J.P. Morgan began coverage of retailers Gap and Limited Brands.

In a morning note, Merrill Lynch downgraded Donnelley (DNY: Research, Estimates) to "neutral" from "buy" and lowered its 2003 earnings estimate for the publishing company to $1.55 a share from $1.40, citing continued pricing pressure. Shares of Donnelley fell 92 cents to $21.38 Thursday.

Merrill cut its rating on Amerada Hess (AHC: Research, Estimates) to "neutral" form "buy," citing disappointing performance of the Ceiba oil field in Guinea leading to lower production levels. Shares of Amerada Hess fell $7.88 to $48.40 Thursday.

The firm also downgraded Cerus (CERS: Research, Estimates) to "neutral" citing "significant launch delays, regulatory uncertainty and a hefty burn rate that will raise liquidity concerns." Shares of the medical device maker fell 8 cents to $14.32 Thursday.

Merrill raised its 2003 profit estimate for Dow component Exxon Mobil (XOM: Research, Estimates) to $2.20 a share from $2.15, citing the gas company's positive quarterly results. Shares of Exxon Mobil fell 62 cents to $33.23 Thursday.

J.P. Morgan began coverage of Gap (GPS: Research, Estimates) with a "neutral" rating saying that, among other factors, they would prefer to wait for a more compelling entry point to purchase the stock. J.P. Morgan also started coverage of Limited Brands (LTD: Research, Estimates) with a "neutral" rating.

The firm upgraded Dun & Bradstreet (DNB: Research, Estimates) to "overweight" from "neutral," citing the risk management provider's strong defensive characteristics. Shares of D&B fell 25 cents to $33.70 Thursday.

Lehman Brothers upgraded Pentair (PNR: Research, Estimates) to "overweight" from "equal-weight" saying it had double-digit percentage earnings per share growth potential in a tough economy. Shares of the diversified manufacturer rose $1.74 to $35.70.

Lehman also raised its rating on Dow Chemical (DOW: Research, Estimates) to "overweight" from "equal-weight" saying the company's cost cutting should help cash flow and that the dividend is safe. Shares of Dow fell $1.10 to $28 Thursday.  

-- from staff and wire reports