Shares of Sirius Satellite Radio plunged 7.67% Tuesday to $3.85 after the Gotham company lowered its target for subscriber growth on disappointing holiday sales.

Sirius now expects to end the year with 5.9 million-6.1 million subs, down from its previous estimate of 6.3 million.

“While strong, this year’s retail sales results since the Thanksgiving weekend have not been at the pace we anticipated,” Sirius CEO Mel Karmazin in a statement.

Shares of larger rival XM Satellite Radio were down too, but less, falling 1.98% to close at $14.32.

XM has cut subscriber growth estimates several times this year and now expects to end 2006 with 7.7 million-7.9 million subs.

Separately, XM Satellite said Tuesday that General Motors will add its radios to more than 1.8 million vehicles being built next year.