* Renesas bounces, up 29 pct; trader says oversold * Olympus up 5 pct on report of tie-up * Spain worries continue to depress sentiment By Sophie Knight TOKYO, May 30 (Reuters) - Japan's Nikkei inched down on Wednesday morning, with a firm yen against the euro pinching exporters, although troubled chipmaker Renesas Electronics Corp staged a dramatic rebound and Olympus Corp leapt on a reported tie-up. The Nikkei share average slipped 1 percent to 8,571.90, while the broader Topix index fell 1.2 percent to 718.22. "At the end of the month window-dressing comes into play, but today the buying is mostly just closing out positions," said Masayuki Otani, chief market analyst at Securities Japan. Softbank Corp put on a solid 2.4 percent and was the top traded stock by turnover after Deutsche Securities upgraded the telecommunication company's rating to "buy" from "hold" and raised its target price to 2,810 yen from 2,570 yen, saying it had an impressive subscriber growth rate. "The market reacted well to signs that a Chinese stimulus programme may be coming yesterday, but now that's priced in it's back to worrying about the euro zone," said Hideyuki Ishiguro, assistant manager of investment strategy at Okasan Securities. "The market is tired of waiting for the Greek election, so the focus is shifting to Spain." Exporters remained under pressure as the yen firmed to a four-month high against the euro after Spain's borrowing costs rose on Tuesday towards the 7 percent level that led other countries to seek a bailout. TDK Corporation, a stock with high exposure to Europe, dropped 3 percent. Renesas Electronics soared 28.9 percent, bouncing back after the troubled chip maker's share price was slashed in half this month and the company was forced to seek 100 billion yen ($1.3 billion) to pay for a proposed restructuring. The stock was the biggest gainer after sliding 16.4 percent as the biggest loser on Tuesday, hitting a record low. "It has been oversold ... They're hoping to get some capital injection, significantly lessening the downward pressure," a dealer at a European brokerage said. Olympus Corp also jumped, gaining 5.1 percent to a one-month high after the Asahi newspaper reported that it was seeking a capital tie-up worth tens of billions of yen with either Sony Corp or Panasonic Corp. Sony fell 2 percent and Panasonic lost 3 percent on the news they could be associated with scandal-ridden Olympus. The Nikkei was out of "oversold" territory, with its 14-day relative strength index at 30.7, but market analysts said it would encounter strong resistance on the upside as most buying was short-covering and buying on dips. "Usually it would find resistance at its 5-day moving average (around 8,593.18), but today it's broken through that without effort," said Otani of Securities Japan. "It's pretty sluggish today, but the next milestone lies around 8,500." The Nikkei is down 16 percent from its year high of 10,255.15 on March 27 and has posted a weekly loss for eight consecutive weeks, its worst run for 20 years, on a deepening euro zone debt crisis and concerns about the slowing global recovery. Volume on the Topix index was light, at 37 percent of its 90-day average. "There won't be any reason for buying in earnest until the euro zone calms down, but right now it's moving in an ominous direction," Ishiguro of Okasan Securities said.