The Tokyo stock market has been on a roller-coaster ride in recent weeks, keeping market participants guessing on whether the volatility is the beginning of a lasting decline.

The 225-issue Nikkei average has plunged roughly 17 percent in a little more than a month, with high-priced information-technology issues coming under severe selling pressure.

Other yardsticks, however, indicate the market as a whole is still performing fairly well.