Global Stock Exchanges Get Live Lesson in Perils of a Shutdown

As stock exchanges around the world decide how to operate at a time of unprecedented market turmoil, the Philippines just offered a real-time lesson.

After two days without trading, equities tumbled 13% as the market reopened Thursday, with investors rushing to liquidate holdings once they could. It’s the reason many other exchanges around the world say they’ll stay open, even as they consider new restrictions like reduced hours or bans on short selling.

“Closing the markets generates even more panic,” Ignacio Cantos, investment director at ATL Capital in Madrid, said by phone. “Nowadays the systems are ready to support ...