LONDON, June 5 (Reuters) - Stock exchanges and other

trading platforms should draw up and make public plans for

dealing with outages to provide greater predictability for

customers, global securities watchdog IOSCO said on Wednesday.

Exchanges worldwide have been hit by glitches and outages

for various reasons, such as software changes.

A glitch at the New York Stock Exchange (NYSE) on Monday

triggered massive swings in the shares of Berkshire Hathaway ( BRK/A )

and Barrick Gold ( GOLD ), and trading halts in dozens

of other companies, before the problem was fixed.

"Where trading venues have effective playbooks and outage

plans in place, this provides market participants with certainty

about the steps that trading venues will take in the event of an

outage," IOSCO, which is comprised of regulators from across the

world, said in a report.

The report highlighted "the need for improved preparedness

and management of market outages to ensure market resilience and

investor confidence".

Exchanges could also set out their "reopening strategies" to

explain the steps taken for restarting trading and how orders

will be managed, the IOSCO 'best practice' guidance said.

Trading venues that run closing auctions that determine

prices used in benchmarks should also spell out what happens

after an outage.

"Where a closing auction cannot be run at the scheduled

time, trading venues may need to consider postponing the closing

auction before cancelling it," IOSCO said.

"If the operation of a closing auction is not possible,

trading venues may need to consider how to ensure the market is

provided with alternative closing prices."

Exchanges could also seek feedback from users for a "lessons

learnt" exercise following an outage, the watchdog said.