Societe Generale SA will make a one-time payment to those who used its daily leverage certificates to short Singapore Airlines Ltd. stock and got wiped out after the carrier’s share price surged following an adjustment for a rights issue.

SocGen said it will pay 30 Singapore cents per certificate, the French bank wrote in a letter to investors on May 12. “The goodwill payment amount is not intended to compensate investors for all loss given the risks investors assumed in purchasing these structured products,” it said.

A price movement of more than 20% within 15 minutes on May 6 led to one of SocGen’s products shorting the stock—DLC SG5xShort SIA—losing all its value after a so-called airbag trigger was activated, the bank said in a statement on Friday. A 5x Short certificate moves inversely to the underlying asset price by a factor of five.

Structured-product investors have faced billions in losses during the global stock rout in March, which was exacerbated by traders taking on more leverage. The Business Times wrote in a report some users of SocGen’s leveraged products for shorting Singapore Airlines have protested against perceived lack of timely disclosure and unfair pricing.

Singapore Exchange has begun investigation into the circumstances leading to SocGen adjustment announcement, the bourse said in response to Bloomberg queries.

“In respect of the adjustment announcement, our regulatory focus is centred on ensuring timely disclosure. We require that adjustments be announced once it is determined, but in no event later than the market day prior to the effective date,” a spokeswoman for the exchange said in an email.

A SocGen spokesperson declined to comment on the probe.