It may be too early to determine conclusively whether high-frequency trading has plateaued, but indications are that the trading methodology has lost some steam amid lower overall trading volumes.

“With falling off trading volumes generally, we’ve also seen HFT volume fall off,” said Kevan Cowan, president of TSX Markets and group head of equities at TMX Group in Toronto.

More than 40% of trading volume on TMX’s Toronto Stock Exchange comes from market participants outside Canada, making the Canadian bourse’s experience with high-frequency trading a reasonable depiction of how it operates globally.

The market share of high-frequency trading in Canada has held about steady, as absolute HFT volumes have fallen off roughly in-line with overall volumes, Cowan told Markets Media on the sidelines of a TMX Trading Conference in May.

Some market participants have said the profitability of high-frequency trading has declined over the past couple years amid more HFT practitioners and institutional traders who are better at fending off the speed players. High-frequency trading has also come under intense scrutiny from regulators in the U.S. and elsewhere, who have signaled new restrictions may be forthcoming.

The recent decline in HFT volumes “may be as much about the regulatory debate around high frequency, which is intensifying, particularly south of the border,” Cowan said. Market participants are wondering “whether or not any regulation will be put in place,” he said.

Regulatory uncertainty could depress high-frequency volumes by potentially discouraging market participants from investing in the technology and personnel needed to maintain a profitable HFT desk.