TOKYO, Nov 1 (Reuters) - Japan's Nikkei fell to a one-week closing low on Friday, dragged down by Sony Corp, Apple Inc supplier Nitto Denko Corp and NTT Data Corp after they sharply lowered their earnings guidance. Gains in Panasonic Corp and mobile operator SoftBank Corp offered some respite, however. The Nikkei fell 0.9 percent to 14,201.57 points, reversing earlier gains and adding to Thursday's 1.2 percent slide. Still, the benchmark was up 0.8 percent this week and is up 37 percent year-to-date. Panasonic climbed 6.2 percent to a 2-1/2 year high after it lifted its earnings forecast while index heavyweight SoftBank rose 3.4 percent on the back of a record six-month profit. SoftBank was the most traded stock on the main board by turnover, followed by Sony, which plunged 11.1 percent, marking its worst one-day decline since October 2008 and knocking about $2.2 billion off its market valuation. The maker of famed Walkman music players to the game console PlayStation slashed its annual operating profit forecast by 26 percent as its struggling TV operations fell back into red. Both Nitto Denko and NTT Data also cut their estimates. Nitto Denko lost 2.1 percent and NTT Data dropped 4.8 percent. Among other top-weighted losers were Ricoh Corp and TDK Corp, off 6.7 and 3.9 percent respectively, after their quarterly results. The broader Topix index lost 0.9 percent to 1,183.03, with 2.73 billion shares changing hands, slightly lower than Thursday's 2.81 billion.