Web publishers join forces to reach prospects at work ; CBS Marketwatch spearheads creation of At-Work Brand Network in first coordinated effort to sell Internet space by day-parts.(Brief Article)

Aiming for advertisers that want to reach prospects as they surf the Net at work, five leading Internet publishers last month launched the At-Work Brand Network.

The effort is the first coordinated attempt by a group of publishers to sell Internet ad space by day-parts across a network of sites reaching people in their offices. It addresses the need, long stated by online advertisers, to reach their target audience by time of day, as they do with other media such as broadcast TV and radio.

The five publishers are CBS MarketWatch, CNet Networks Inc., NYTimes.com, USAToday.com and Weather.com.

Ad agencies Avenue A and White Horse are the charter …