The investment heavyweight has boosted its interest in the New York-listed shipowner to 5.2%, an SEC filing shows.
Its 4,696,318 shares are worth a shade over $33m based on the last trade of DHT shares in the US.
Earlier in the decade Blackrock was one of the key backers of DHT and its largest external shareholder.
In 2012, it sold down some of its stock, with filings from the time showing it was left with 1.51%
