Updated from 11:06 a.m. ESTHeavy selling in Sprint PCS ( PCS) was dragging down the wireless sector Tuesday as concerns grew about subscriber growth and the industry's financial outlook. Sprint was down $3.26, or 27%, to $10.60 in recent trading, while Sprint Corp. ( FON), Sprint's non-wireless division, was down $1.75, or 11%, to $14.27. Shares of both companies were at all-time lows. Both Merrill Lynch and Morgan Stanley downgraded Sprint PCS this morning after Monday's warning. Merrill downgraded the wireless operator to neutral from strong buy, and Morgan Stanley lowered its rating to neutral from buy.