Japanese executives are warning that sharp currency swings and a persistently weak yen are becoming a broader economic risk even after official support for the currency. The yen rose about 5% after Japan's intervention around July 30 to August 3, following a slide to nearly 164 per dollar in July, and Nomura estimated the Ministry of Finance spent about 14.1 trillion yen, or $88 billion, in that period, above the combined 11.7349 trillion yen used on April 30, May 4 and May 6. Executives from Mitsubishi Electric, Mitsui & Co and Mitsubishi Corp said the weak yen raises import costs, distorts forecasts and makes investment decisions harder despite benefits to exporters and overseas earnings. A March JETRO survey found 120-124 yen per dollar was the most desirable range for nearly a fifth of companies, while only 11% favored levels above 150.