A bitcoin rally drove a $20.91 billion gain in the value of Strategy's crypto holdings during the third quarter.

The bitcoin treasury company reported the gain on digital assets for the quarter-ended Sept. 30 in a Monday filing with the Securities and Exchange Commission. The price of bitcoin rose substantially during that period.

Strategy said that as of Sept. 30, the value of its bitcoin holdings exceeded their cost basis. The company said it reversed a $4.12 billion deferred tax asset as of June 30 with respect to the loss on its bitcoin holdings, and that the associated valuation allowance against that amount was released.

Strategy is now estimating a deferred tax expense of around $1.88 billion, down from about $6 billion, excluding other deferred tax assets and related valuation allowances. The company estimate that as of Sept. 30 it had a digital asset carrying value of $70.82 billion.