CHARLOTTE, NC/NEW YORK - Capital One Financial Corp plans to buy ING Groep NV's US online bank for $9 billion in cash and stock, leapfrogging up the ranks of the largest US banks, the companies said on Thursday afternoon.

The McLean, Virginia-based bank, best known for its credit card unit, will pay $6.2 billion in cash and $2.8 billion in stock.

That will help ING, a Dutch banking and insurance conglomerate in the middle of a breakup, repay the remainder of the money it owes to the Dutch government for a 2008 bailout. The company also will receive a 9.9 percent stake in Capital One as part of the deal and will have the right to name a director to the US bank's board.

The deal is the latest step in Capital One's efforts to transform itself from its credit card lending roots. Adding ING Direct USA's assets would bump Capital One up two places in the rankings to make it the nation's seventh-largest bank by assets, according to SNL Financial, a financial services data firm.

"Capital One is picking up market share at what they feel are reasonable rates," said Matt McCormick, portfolio manager with Bahl & Gaynor Investment Counsel. "They're thinking that now's the time to pick up market share by acquisition. It's a risk, but it's a calculated risk."

The US bank will raise $2 billion in new capital and will offer debt of about $3.7 billion to help finance the deal, which is expected to close around the end of the year.

The Wall Street Journal had earlier reported the deal on Thursday.

According to SNL Financial, ING Direct USA is the 20th-largest US bank. As of March 31, Capital One had $199.3 billion of assets.