Bank of America and PNC Financial Services plan to sell 42m shares through a secondary offering of the investment managerâ??s stock.

BofA will sell 34.5m shares and the offering will reduce BofAâ??s ownership stake, both common and preferred shares, in BlackRock from 34 per cent to less than 13 per cent.

PNC, a Pennsylvania-based regional lender, will sell up to 7.5m shares and reduce its combined holdings from 24 per cent to 20 per cent.

BlackRock had retained the right to block any sale of each bankâ??s stakes.

The offering will not affect BlackRockâ??s distribution agreement with BofA, which sells the companyâ??s funds through its wealth-management arm.