The Nihon Keizai Shimbun Inc. said Wednesday that a special quotation fixation day was a major factor behind the heavy trading of specific issues during the two days before the announcement of a change in the benchmark Nikkei stock average’s components in April, denying a report linking the deals to possible insider trading.

Nihon Keizai was responding to a Monday report by Kyodo News that said the Securities and Exchange Surveillance Commission has asked securities houses to submit reports over possible insider trading as almost all of the 30 shares dropped from the index experienced dramatic rises in trading shortly before the announcement of the change in the index.

Nihon Keizai announced the reshuffle on April 15. It took place on April 24.

“There is a factual misconception,” in the report, the newspaper said.

The major economic daily, which controls and operates the 225-issue Nikkei stock average on the Tokyo Stock Exchange, said that April 14 was the SQ fixation day for settlements of April contracts for futures and options.

April 13 was therefore the last day of trading for April futures and options contracts, the newspaper said, adding that trading is normally heavy on such days.

Nihon Keizai said the trading volume of the 30 stocks on April 14 accounted for 4.2 percent of the total trading volume on the first section, nearly equal to that on March 13, the previous SQ fixation day.

“Kyodo’s report may lead to misunderstandings, since it makes no mention of the fact that stock trading increases on SQ fixation days,” a Nihon Keizai spokesman said.

Officials at the TSE said SQ fixation days for futures and options trading are set in March, June, September and December.

While trading is especially heavy on those days, SQ fixation days in other months are only for options trading, and market transactions should not increase as dramatically, according to the TSE officials.