Updated from 4:14 p.m. EDTRadioShack's ( RSH) bad news may drag down several companies in the wireless sector. Specifically, Sprint PCS ( PCS), Verizon Wireless and Qualcomm ( QCOM) may see potential downside in sales in the upcoming quarters. RadioShack announced today it expects third-quarter revenue to decline 3% to 4% and earnings to be reduced to 23 cents to 26 cents, down sharply from its previous estimate of 33 cents. Wall Street consensus was 34 cents, according to a Thomson Financial/First Call poll. July sales rose 2%, but the company told analysts that August sales "deteriorated dramatically" and blamed worsening consumer demand. RadioShack shares plunged $4.74, or 16.37%, to $24.21 on news of the disappointing report, and investors may be in for another disappointment from the wireless sector. Unlike other major electronics retailers, which have also suffered a disappointing year due to slackening demand, RadioShack derives the lion's share of its revenue from sales of electronic accessories and cell phones, and that puts several companies in the sector in a direct line of fire, analysts say. Sprint PCS gets some 25% of its sales through RadioShack's 7,200 nationwide outlets. Verizon Wireless sees about 10% to 15% of its sales through the retailer, according to analyst estimates. What unites these two companies is the common technology platform -- the Qualcomm ( QCOM)-produced Code Division Multiple Access platform.