(Reuters) – Jane Street Global Trading, a U.S. company, has filed a lawsuit against the London Metal Exchange seeking $15.3 million. This is the second legal action it has had to face this week.

Hong Kong Exchanges and Clearing has been investigating the LME. It is owned by Hong Kong Exchanges and Clearing and suspended nickel trades and cancelled them on March 8, due to high volatility. Prices rose to $100,000 per ton within hours.

Jane Street representatives stated in a statement that the decision to cancel nickel trading “during periods of heightened volatility severely undermines market integrity and sets a dangerous precedent which calls into question future contracts.”

In a statement, the Hong Kong bourse stated that it considered the claims of the U.S. market maker and quantitative fund to be without merit. The LME would vigorously contest them.

The LME announced Monday that Elliott Associates was suing it for $456 Million for cancelling Nickel trades.

HKEX also responded to Elliott’s lawsuit by saying that the LME must take steps to ensure the safety of the whole market when there is disorder in trading.