With JP Morgan acquiring WaMu's deposit base, they rocketed above Citigroup as the biggest bank in terms of deposits. This increases concentration among the largest five deposit holders to a massive 45% by market share (assuming $7 Trillion in total deposits), but I'm not so convinced that bigger is better.
And further concentration is likely... per CNNMoney.com:
Wachovia is reportedly mulling a deal with another large bank, including Citigroup and Spain's Banco Santander, according to reports published Friday afternoon.Should Citi and Wachovia merge, the big 3 (Citi, JP Morgan, and Bank of America) would combine for almost $3 Trillion in total U.S. deposits.
Just another data point as to why additional regulation and oversight is so important...
Source: Infectious Greed