The move follows the sudden plunge in an exchange-traded note called VelocityShares Daily 2X VIX Short-Term ETN, or TVIX, which lost 60 percent of its value in a short span of March.
The warning would be similar to one that pops up when investors trade options related to volatility, which are more complex than stocks. The note, which pops up at the final verification stage of a trade, will serve as a last warning to a customer. Schwab’s review and consideration of a warning for investors is significant because it comes at a moment after federal and state regulators have zeroed in on volatile trading and other activity involving exchange-traded notes.