NEW YORK ( TheStreet) -- Apple ( AAPL) was a loser in premarket trading on Wednesday as investors responded to the tech giant's third-quarter results, released after market close on Tuesday. The iPhone maker's shares fell 4.66% to $572.89 after Apple missed analysts' top- and bottom-line estimates. The Cupertino, Calif.-based firm also offered weaker-than-expected fourth-quarter guidance. Speaking during the conference call to discuss the results, Apple Chief Financial Officer Peter Oppenheimer cited a number of reasons for the revenue and earnings miss, including economic weakness in Europe, Australia, Canada, and Brazil. With the eagerly anticipated iPhone 5 expected to debut in September or October, the tech giant clearly experienced a lull in iPhone sales during its third quarter. Apple was also one of the most active premarket Nasdaq stocks on share volume of 576,420. Netflix ( NFLX), however, was an even bigger loser, tumbling 18% to $65.81 after releasing its second-quarter results on Tuesday. While Netflix's second-quarter earnings beat expectations, investors balked at the company's weak outlook for the rest of the year. Symantec ( SYMC), however, was a big gainer after announcing its first-quarter results and an executive reshuffle. The security specialist, which was scheduled to report its numbers after market close, posted revenue of $1.67 billion and earnings of 43 cents a share before market open, comfortably above analysts' forecast of $1.65 billion and 38 cents a share. The Mountain View, Calif.-based firm also announced that CEO Enrique Salem has stepped down, to be replaced by Steve Bennett, the company's chairman. Symantec shares climbed 7.78% to $14.20 before market open. Riverbed ( RVBD) was another major gainer following solid second-quarter results, which came in above analysts' expectations on Tuesday. The WAN optimization specialist also offered robust guidance, pushing the company's shares up 24.40% to $18.10. Juniper ( JNPR) was another winner following the company's strong second-quarter results, released on Tuesday, which topped both its own and Wall Street's expectations. The Cisco ( CSCO) rival;s shares climbed 5.97% to $15.70 before market open. Juniper and Riverbed also announced a technology partnership. Under the terms of the deal, Juniper will license Riverbed's application delivery controller technology for around $75 million. The two companies will also integrate Riverbed's Steelhead mobile technology into Juniper's Pulse Virtual Private Network (VPN) software.