Even at his advanced age, Berkshire Hathaway (BRK.A  ) CEO Warren Buffett remains one of the sharpest minds in the market. Thus, it's quite notable that he has been using the elevated volatility of the past year to deploy his large cash pile into a couple of new positions and heavily into his favorite ones.

This comes after several years of Buffett choosing to sit on his hands. Even during the sudden drop in the spring of 2020 due to the coronavirus, Buffett didn't do any serious buying. Later, he said that due to the federal government and Federal Reserve's swift response, the bargains that he typically looks for never materialized. As a result, Berkshire's cash holding reached above $160 billion.

Now, the situation is much different as Berkshire's cash pile is just over $100 billion as Buffett's buying spree continues although at a slower pace. In Q2, he bought $3.8 billion of stock, down from $41 billion in Q1. The company also bought back $1 billion in Berkshire stock. Of course, some of the buying is reflective of his co-portfolio managers, Ted Weschler and Todd Combs.

Some of his most notable buys included adding 3.9 million shares of Apple (AAPL  ), which is already his largest position. Currently, Berkshire owns 895 million shares in Apple, worth about $122 billion. It makes up 41% of Berkshire's total portfolio.

Recent returns are quite strong for Apple which is less than 10% off it's all-time highs and up more than 30% from its mid-June lows. Many believed that Apple posed a unique risk as 95% of the company's manufacturing takes place in China.

He's also been an aggressive buyer of Occidental Petroleum (OXY  ). In Q2, he added 13.9 million shares. Currently, he owns a mix of stocks and warrants which makes up about 30% of Occidental's total float. This is increasing speculation that Buffett's endgame is a buyout of the entire company especially as an integrated oil & gas producer would be a nice complement to the other assets in Berkshire Energy.