Berkshire, which Buffett manages and effectively controls, owns insurance companies and a mortgage lender outright. Berkshire also has stakes in publicly traded banks including US Bank, Wells Fargo, and American Express (they converted into a deposit-taking bank company in the wake of the financial crisis). Then there's Bank of America, in which Berkshire has warrants to buy a stake < 10%, but they likely won't be exercised until they're about to expire.

Beyond this, managers and policy makers listen when Buffett talks/writes; an outcome of his 50-year track record in investing and managing at Berkshire. I personally don't think there's anything sinister going on.

You can get a really good overview of Berkshire as a company, including its operating companies, investment philosophy, and current investment holdings from the annual letters that Buffett writes: http://berkshirehathaway.com/letters/letters.html

If you want to see exactly what securities Berkshire owns, you can look up the 13F filings on http://edgar.sec.gov

Control is a magic word and requires certain minimum percentages of shares to be held.