Delta Air Lines has hired a law firm and will seek compensation from Microsoft and CrowdStrike over the global cyber outage earlier this month that disrupted flights around the world, CNBC reported on Monday.

The Atlanta-based airline has been the slowest among major U.S. carriers to recover, following the tech failure which led to more than 2,200 flights cancellations on July 19.

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Delta has cancelled more than 6,000 flights so far, leaving hundreds of thousands of travelers stranded. Analysts estimate that the impact on its bottom line could be in the hundreds of millions.

The U.S. Transportation Department announced last week that it would open an investigation into the carrier, and Delta has stated its intention to cooperate.

Microsoft, Delta, CrowdStrike and law firm Boies Schiller Flexner did not immediately respond to Reuters' requests for comment.

Shares of Crowdstrike were down about 2% in after-hours trading.