Following four months of spectacular growth, security token trade volumes have crashed by nearly 60%.

From May through August, monthly volume gains for the sector ranged between 113% and 280%, posting record highs that increased from $998,000 to nearly $22 million, according to Security Token Group’s reports.

The big run-up means that despite the massive slump in trade activity, September was still the second-strongest month on record for security tokens, with more than $9.15 million in combined trade volume.

tZERO’s TZROP token, which represents equity in the alternative trading system, comprised more than half of total trade volume, at $5.3 million, down from August’s $11.8 million.

TZROP declined just 2% in price over the month, from $7.26 to $7.10; however, it traded within a range between $6 and $7.90. TZROP is the second-most popular security token, with a market cap of $128 million, making it the 80th-ranked crypto asset according to CoinMarketCap

Overstock’s OSTKO digital security, which represents equity and voting rights in the company, drove $3.6 million in volume, down from $9.6 million last month. OSTKO also closed the month fairly flat at 1.5% down, despite producing a wide trading range between $48 and $65. OSTKO is the largest security token with a $321 million capitalization, making it as the 50th-ranked crypto asset overall.

Top 5 security tokens by market cap: STOMarket

The combined market capitalization of security tokens increased by nearly 4% to $528.6 million during September, owing to the addition of three tokens trading on the Seychelles-based MERJ Exchange.

MERJ’s tokens include its own native security token, MERJ-S, which was issued in a token sale that raised more than $450,000 last month; Uprets’ OST1 token representing fractionalized ownership in a Brooklyn apartment building; and Minervest’s MSTV-S token.

The three tokens represent nearly $24 million in assets, although none of them changed hands during September.