Updated from 8:17 a.m. EDT

Shares in

Corning

(GLW) - Get Report

, the world's top maker of optical fiber and cable, tumbled 8% Monday on rerports the company was in talks to buy

Nortel Network's

(NT)

optical parts unit.

The Wall Street Journal

cautioned that the potential deal, which involves Nortel selling its optical parts unit to Corning, is not imminent and could fall apart.

Official sources at Corning and Nortel declined comment, with spokespersons at both companies saying they don't comment on "rumors or speculation."

The news moved the stock prices of both companies. In midday trading, Corning finished Monday regular trading down 32 1/4, or 11.4%, at 251, while Nortel closed up 1 3/4, or 2.2%, at 83, after reaching a 52-week high of 84 1/4.

The talks center around a stock swap that would give Ontario-based Nortel more than 50% of Corning, with Corning maintaining its independence and owning the optical parts unit.

The merger would follow the recent deal in which

JDS Uniphase

(JDSU)

, the world's largest maker of fiber optics components, agreed to

buy

SDL

(SDLI)

in a deal valued at the time close to $41 billion. Corning, N.Y.-based Corning reportedly lost out in the bidding for SDL.

The rumored price tag of $100 billion is based largely on expected growth in the optical-parts business, according to the article, which estimated the unit's revenues at around $1 billion.