TOKYO, Oct 24 (Reuters) - The Nikkei average slid 5 percent on Friday, dragged down by Sony Corp (6758.T: Quote, Profile, Research) after it halved its full-year profit forecast, while spooked investors dumped shares in other exporters on fears about their earnings prospects.

As of 0116 GMT, the Nikkei .N225 was down 3.7 percent at 8,144.30. The broader Topix .TOPX lost 3.3 percent to 842.89. (Reporting by Aiko Hayashi)