What are America's investing legends buying?

(CNNMoney.com) -- Whether it has been investing in gun manufacturers and energy companies or ditching food suppliers, America's best known investors were busy in the second quarter.

Here's what a few of them were up to, according to recent filings with the Securities and Exchange Commission.

Warren Buffett: Berkshire Hathaway (BRKA, Fortune 500), led by legendary investor Warren Buffett, disclosed that it upped its position in Johnson & Johnson (JNJ, Fortune 500) in the second quarter by 73%, despite the drugmaker's ongoing legal troubles.

The conglomerate reported that it acquired 4.4 million shares of payment processor Fiserv (FISV, Fortune 500) to its portfolio -- a new position for Berkshire -- and boosted its stake in health care companies Becton Dickinson (BDX, Fortune 500) and Sanofi-Aventis (SNY).

At the same time, Berkshire cut its stake in oil company ConocoPhillips (COP, Fortune 500) by 15% and shed shares of Kraft (KFT, Fortune 500) and Procter & Gamble (PG, Fortune 500), reducing its stake by about 1% in each company during the quarter. (more)