LONDON, July 24 (Reuters) - U.S. Fortune 500 companies,

excluding Microsoft ( MSFT ), will face $5.4 billion in

financial losses from the recent CrowdStrike ( CRWD ) outage,

insurer Parametrix said on Wednesday.

CrowdStrike's ( CRWD ) faulty update to its security software crashed

computers powered by Microsoft's ( MSFT ) Windows operating system,

disrupting internet services across the globe and affecting a

broad swathe of industries including airlines, banking and

healthcare.

Insured losses from the outage will likely total $540

million to $1.08 billion for the Fortune 500 companies,

Parametrix said in a statement.

Major cyber insurer Beazley said this week it had

no plans to change its guidance on its combined ratio - a key

measure of underwriting profitability - after the mass IT

outage.

The global insurance and reinsurance industry is likely

to

avoid any major financial impact

from the outage, ratings agency Fitch said on Monday.