The final word on the banking sector comes from the 2007 bank supervision (PDF) report from the Central Bank of Kenya.

Notes:
– CBK ranks banks using CAMEL (capital adequacy, asset quality, management quality, earnings, and liquidity); 10 banks are strong (down from 13 in 2006), 27 satisfactory, 8 are fair and none were ranked marginal or unsatisfactory. Overall the banking sector totaling 951 billion in assets (~$14 billion)is satisfactory, but with 6 large banks controlling 58% of the industry
– Increase from 575 to 740 branches (293 in Nairobi) in 2007 [all province had increase in branches led by Nairobi (54) and rift valley (46) with only central bank with a decline in branches (-2)]
– Number of deposit accounts increased by 42% to 4.7 million
– Regulatory issues tacked include disaster management, IFRS, Basel II, licensing of shariah banks
– The sector employed 21,657 in 2007 (4727 management, 3865 supervisory, 12,773 clerical, 292 other) up from 15,568 in 2006
– Some of the (97) forex bureaus flout laws such as not recording transactions, money laundering, transfer of ownership, operating parallel hawalla accounts, liquidity
– Coming up: microfinance institutions will be licensed, credit reference bureaus will become operational, capital increases expected

And where are the 4.68 million (deposit) bank accounts kept?

Bank, No. of accounts, (no of branches)
Equity 1,840,332
Cooperative 556,073 (54)
Kenya Commercial 487,667 (135)
Family Finance 465,308
Barclays 428,531 (95)
National Bank of Kenya 233,026 (34)
K-Rep 169,796 (26)
Standard Chartered 131,618 (34)
Housing Finance 45,842 (10)
Stanbic 31,906 (8)
Diamond Trust 29,589 (13)
Others are Consolidated 25,078 (12), CBA 23,657 (17), I&M 22,053 (10), NIC 21,452 (15), Fina 14,446 (7), CFC 12389 (8), Transnational 11,053 (9), and Citibank 2,927 (3)