BlackRock is altering the distribution of voting rights among its largest shareholders in a complicated arrangement that involves exchanges of common and preferred shares.

As a result of the adjustment, Merrill Lynch will still retain its 49.5 per cent stake in BlackRock but its voting rights will be slashed to 4.9 per cent. At the same time, PNC Financial Services will exercise 47 per cent of the voting rights, while retaining 33 per cent of the ownership.