(Reuters) -Istanbul’s stock exchange operator suspended trading until Feb. 15 and cancelled all Wednesday’s trades in the wake of devastating earthquakes that struck Turkey and Syria on Monday.

The tremors rocked Turkey and Syria in the early hours of Monday, with hundreds of buildings collapsing and the combined death toll across both countries climbing above 12,000.

Turkey’s Borsa Istanbul suspended trading on its equity and derivatives markets within minutes of opening after market-wide circuit breakers stopped the slide in the main index at 7%.

The country’s benchmark index fell as much as 16% from its Friday close before the Wednesday trades were cancelled. To Tuesday’s close, the loss is 9.9%.

Trading volumes were significantly below regular averages at only 2.24 billion trades on Tuesday, compared with Friday’s 4.14 billion.

“Due to the increase in volatility and extraordinary price movements after the earthquake disaster; in order to ensure the reliable, transparent, efficient, stable, fair and competitive functioning of the markets, Equity Market and Equity & Index Derivatives in the Derivatives Market have been closed,” Borsa Istanbul’s statement said on Wednesday.

“Considering the low transaction volume that does not allow efficient price formation, all trades executed in the closed markets on Feb. 8, 2023 will be cancelled,” the market operator said.

An exchanged-traded fund that tracks performance of the Turkey MSCI index, both priced in dollars, is down almost 13% this week and 20% for the year.

The market capitalization of the MSCI index fell from $39.7 billion at the end of last week to $35.8 billion at the close on Tuesday according to Refinitiv data.

“They’ll have to reopen at some point and allow trades to take place. Waiting delays the inevitable price changes,” said Brian Jacobsen, senior investment strategist at Allspring Global Investments.

“Reopening and then cancelling trades seems unorthodox, but there have been a lot of unorthodox things coming out of Turkey.”

Index provider FTSE Russell said its indexes will reflect Tuesday’s close when trading resumes next week and they are monitoring for further closures. Its guidance shows FTSE could extend this for up to 20 trading days.

MSCI did not respond to a request for comment.

Meanwhile, domestic investors started an online petition calling for the reversal of all trades that took place since Monday.

“We call for the reversal of all trades that took place on Borsa Istanbul as of February 6, 2023 and the closure of the exchange during the national mourning period,” read the petition, which received over 10,000 signatures within hours.

The quakes have forced major corporations like BP to declare force majeure in their disaster zone operations in southern Turkey.

Turks beset for years by soaring inflation and currency crashes have piled into the country’s stocks in recent months, lifting the main index by 200% last year.

Murat Bakan, a member of parliament from the main opposition, said on Twitter: “Suspending the exchange is not enough. Trades that took place on Istanbul stock exchange following the earthquake must be cancelled.”

The reversal of trades will protect the rights of 500,000 investors, Bakan said, adding some people might still be awaiting help or not have Internet access.

Local investors now account for 70% of stock holdings, up from 35% in 2020, while the share of foreign investors holding Turkish stocks has dipped to below a third.

Many international investors have quit in recent years amid recurring market turmoil and Ankara’s embrace of unorthodox economic and monetary policies, including cutting interest rates in the face of soaring inflation.

(Reporting by Azra Ceylan; additional reporting by Karin Strohecker and Marc Jones in London, Rodrigo Campos in New York and Ezgi Erkoyun in Istanbul; Editing by Daren Butler, Deepa Babington and Josie Kao)