Extreme volatility in the VIX-futures market during trading after-hours on Monday has led Toronto-based Horizons ETFs Management (Canada) Inc. to halt trading and suspend new subscriptions for units of certain ETFs, the firm announced on Tuesday.

Specifically, Horizons has declared a trading halt on units of Horizons S&P 500 VIX Short-Term Futures Daily Inverse ETF and a temporary suspension of new subscriptions for units of BetaPro S&P 500 VIX Short-Term Futures 2X Daily Bull ETF.

“The unexpected level of volatility has impaired the trading of the underlying derivatives used by many VIX-related exchanged-traded products that aim to provide inverse exposure to the S&P 500 VIX short-term futures index,” the firm says in a news release.

Horizons continues to monitor the trading activities in these underlying derivatives and will advise if any further action on either fund is required.

The firm also temporarily suspended redemptions and new subscriptions for Horizons S&P 500 VIX Short-Term Futures Daily Inverse ETF.  Trading for the fund resumed at approximately 13:45 ET.

The units of BetaPro S&P 500 VIX Short-Term Futures 2X Daily Bull ETF will continue trading during market hours. Horizons predicts that the secondary market will continue to provide unitholders with a forum to sell units at a price reflective of the net asset value per unit.

That said, the firm also anticipates that purchases of new units at the available offer price on the secondary market will not be reflective of the underlying net asset value per unit.

As such, Horizons strongly discourages investors from purchasing new units of BetaPro S&P 500 VIX Short-Term Futures 2X Daily Bull ETF at this time.

Update: At approximately 15:45 ET, the Horizons announced the resumption of new subscriptions for BetaPro S&P 500 VIX Short-Term Futures 2X Daily Bull ETF, with a temporary capped limit until further notice.