The stock dropped $1.83 to $38.63 on Nasdaq following reports in the Wall Street Journal and the New York Post that eBay may buy Skype for as much as $5 billion.
An eBay spokesman declined to comment. A representative for Luxembourg-based Skype, whose software allows consumers to make free telephone calls around the world over the Internet, said the company would not comment on the reports.
Independent industry analyst Jeff Kagan said Thursday a deal between eBay and Skype would represent a major strategic shift for eBay.
"This would be a big move away from the auction business for eBay and could be a sign of a change in strategy for the company as the telecommunications industry begins to explode again," Kagan said in an email.
Last month, in an interview with Reuters, Skype co-founder Janus Friis shrugged off suggestions that Skype may be acquired by bigger rivals, such as Google, which have more resources to take on big telephone operators that are now launching their own Internet telephony and messaging services.
At the time, Friis said Skype had invested heavily in infrastructure and planned to remain a standalone company.