Shares of the America's largest satellite operators were taking a tumble today. This is fueling new rumors about an inevitable merger between Sirius Satellite and XM Satellite--as the industry faces an onslaught of competition from Wi-fi devices to digital music players.

Sirius stocks were down 31 cents at one point to $3.87 a share, and XM stocks were down 27 cents to $14.36 a share.

Sarah McBride is a reporter for The Wall Street Journal. She told CNBC's Sue Herera on "Power Lunch" that these companies might have over estimated the market for satellite radio. She also said it's too early to tell if there's enough business for them both. She cited that gift certificates are not being bought as much as before--because the recipient does have to pay the monthly subscription bill.