JPMorgan's companies own 114.4 million shares in Moscow Exchange worth 11.43 billion rubles ($202 million) based on Wednesday closing price.
"One fund from the JPMorgan Chase family increased its stake in Moscow Exchange, having crossed the threshold of 5 percent. This demonstrates a high level of confidence in the company and is a signal for other investors," the stock exchange's representative told Reuters.
The Central Bank of Russia is the largest shareholder of Moscow Exchange with a 11.8 percent stake.
Reporting by Anna Pruchnicka in Gdynia, additional reporting Zlata Garasyuta in Moscow, editing by David Evans