Japan's equity market overhaul may cut the companies in the benchmark gauge by a few hundred, and that won't be enough for investors, according to Goldman Sachs Group Inc.

The country's landmark revamp could reduce the number of stocks in the Topix index by about 450 to 550, Goldman strategist Kazunori Tatebe said. That's much fewer than initially expected, he said.

"They have undeniably fallen short of investors' initial expectations, especially regarding hopes for a more streamlined Topix," Tatebe said in an interview. "We'd hoped the number of stocks could be cut down by quite a bit."