Warren Buffett and Carl Icahn’s investment firms provided updates of their stock holdings to regulators on Thursday. In doing so, they opened windows into what they considered to be the best money making ideas and what they thought were duds.

The reports cover the first quarter, which ended March 31. Any more recent investments or sales will not be disclosed until later.

Buffett, a pillar of conservative investing through his company Berkshire Hathaway (BRKA), bumped up his stakes in a number of blue chip stocks. Berkshire’s ownership in Walmart (WMT) grew 17% to 58 million shares during the period from the end of 2013. With the addition of 8.6 million shares, the stake’s value grew to close to $660 million based on the stocks closing price Thursday.

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Additionally, Berkshire added 11 million shares of Verizon Communications (VZ) valued at close to $525 million. But the purchase was potentially small enough that it was handled by one of Berkshire’s investment mangers, and not Buffett himself. Berkshire also modestly increased its stake in IBM (IBM), among the company’s biggest holdings, by 233,000 shares to a total of 68.4 million shares.

For other companies, Berkshire had a dimmer view about their investment prospects. For example, it cashed out a quarter of its holdings in General Motors (GM), the automaker that is now under fire for failing to quickly recall cars with defective parts, for a total holding of 30 million shares. Berkshire also cut its stake in Phillips 66 (PSX) by 64 percent to 9.7 million shares.

Carl Icahn, the activist investor whose strategy is to bludgeon corporate boards into submission, continued with his tech centric strategy of late. His firm, Icahn Associates, reported that it loaded up on 27.8 million shares of eBay (EBAY), the online-auction company along with another 2.8 million shares of Apple (AAPL), increasing its total stake in the company by 60% to more than 7.5 million shares worth around $4 billion.

Icahn had been haranguing eBay to spin off its PayPal online payments unit, he but agreed last month to end the tussle in exchange for a say in who filled a board seat. He had also pushed Apple CEO Tim Cook to increase stock buybacks as a way to prop up the company’s shares. Ultimately, Icahn withdrew his threats of a proxy fight after Apple took some of his advice to heart and increased its share repurchase program.

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At the same time Icahn was adding shares in Apple and eBay, he sold off some of his holdings in Netflix (NFLX), the online video and DVD service. Thursday’s filing showed that his firm owned 2.2 million shares worth $790 million compared with 2.7 million at the end of 2013, valued at $981 million. Ichan had bought a large stake in Netflix last year after the company’s shares took a nosedive, only to remarkably recover and become one of the best performing stocks last year. He has since been taking his substantial profits off the table.