Warren Buffett's Berkshire Hathaway (BRK.A - Get Report) has been boosting its stake in e-commerce giant Amazon.com  (AMZN - Get Report) , with the Omaha, Nebraska-based holding company revealing in a government filing on Wednesday that it boosted its stake in Amazon by 11%.

In a quarterly filing with the Securities and Exchange Commission, Berkshire Hathaway disclosed that as of the end of the second quarter it now owns 537,300 shares of Amazon, worth $947 million.

Buffett announced his firm's initial Amazon investment in May at the company's annual shareholders' meeting, but said that it was "one of the fellows in the office that manage money" who bought the shares on behalf of Berkshire.

Buffett also slightly increased his bets on banks, which have been taking it on the chin this month - this week in particular - amid concerns slowing economic growth and an inverted yield curve will ding profits.

Acccording to the filing, Berkshire increased its stake in Bank of America (BAC - Get Report) by 3.5% during the last quarter. It also raised its holdings of US Bancorp (USB - Get Report) by 2.4%. Its holdings in other banks, including Wells Fargo (WFC - Get Report) and JPMorgan Chase (JPM - Get Report)  , were unchanged.

Shares of Amazon were up 1%, or $17.67 a share, at $1,780.63 in early trading on Thursday. 

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