Look like they own 49% of the the airline, not capacity...
49% equity stake = 49% ownership.

Additionally they own 25% of the voting rights (which is the max limit allowed by law)



To cement the relationship, the parties have signed a letter of intent under which DHL will invest $150 million (119 million euros) to acquire a minority 49 percent equity stake in Polar, including a 25 percent voting interest, consistent with all U.S. laws and regulations. The payment will be in cash, $75 million to be paid upon closing of the transaction, and $75 million to be paid in two installments on January, 15, 2008 and Nov. 17, 2008, subject to certain acceleration provisions. In addition, DHL will enter into a 20-year block space agreement with Polar to obtain guaranteed capacity on routes to major Asian destinations.

DHL: Press Releases