• by Joe Mandese  @mp_joemandese, January 7, 2013

In a wide-ranging revision of advertising and media-related stock ratings, influential Wall Street analyst Brian Wieser has downgraded two of the digital industry’s flagships -- Facebook and Yahoo -- to “hold” from “buy” ratings.

While Wieser, who is the senior research analyst for Pivotal Research Group, maintained the ratings for all other stocks he tracks in the sector, he did raise the target price for several of them, including Yahoo, and especially Omnicom (see below).

Wieser said the changes reflect the sector, as well as the general economy’s shift to a “‘newer’ normal,” and that the “tweaks” in his recommendations reflect that 2013, “on balance, not be too dissimilar from last year. However, we feel that this year may feature an enhanced bias among advertisers towards making decisions on a just-in-time basis (where possible) in order to maintain flexibility in the event that sudden and long-lasting shocks hit the economy.”

• Google: $840, up from $800 previously. Maintain BUY

• Facebook: $30 (no change). Downgrade to HOLD from BUY

• Yahoo: $22, up from $21 previously. Downgrade to HOLD from BUY

• Omnicom: $61, up from $55 previously. Maintain BUY

• Interpublic: $15, up from $14 previously. Maintain BUY

• WPP: 900p / $72, up from 870p / $70 previously. Maintain HOLD

• CBS: $49, up from $43 previously. Maintain BUY

• Viacom: $75, up from $73 previously. Maintain BUY

• Discovery: $73, up from $57 previously. Maintain HOLD

• Nielsen: $33, up from $31 previously. Maintain HOLD