11:23 ET SIRI plunges into red amid enormous volume 3.75 -0.07: Sirius Satellite shares have come down sharply from their morning high of $4.20 following comments by SG Cowen (see 08:19 update) and a downgrade by Stifel Nicolaus (see 10:28). Specifically, Stifel Nicolaus cut its rating to Mkt Perform from Outperform amid concerns that traders who bought the stock ahead of expected positive announcements later this week at the Consumer Electronics Show may sell into the actual news. While firm believes co could show some slight upside to Stifel's 241k year-end 2003 est and 709k forecast for net additions in 2004, firm isn't looking for any major announcements. However, Stifel thinks competitor XM Satellite may surprise strongly to the upside with 2004 guidance of 1.7-1.8 mln vs 1.4 mln consensus net adds.