<div id="readability-page-1">Billionaire Ken Griffin, CEO of hedge fund Citadel Advisors, was busy during the second quarter. He and his team went shopping and substantially increased the firm's stake in some stocks, while also buying new ones. Some of the biggest names on Wall Street, including Microsoft (MSFT -0.02%) and Apple (AAPL 3.62%), were among the companies whose shares Griffin bought during the period. These are two of the largest companies in the world by market cap that have generated life-changing returns over the long run. Both have also made moves in the fast-growing artificial intelligence (AI) market. But are these tech leaders still attractive to long-term investors with market caps above $3 trillion? Let's find out. <img src="https://imageproxy.pbkrs.com/https://media.ycharts.com/charts/8e0e5f1fa40313eccf0c37d28326d569.png?x-oss-process=image/auto-orient,1/interlace,1/resize,w_1440,h_1440/quality,q_95/format,jpg" width="720" height="473" original-src="https://imageproxy.pbkrs.com/https://media.ycharts.com/charts/8e0e5f1fa40313eccf0c37d28326d569.png"/> MSFT Total Return Level data by YCharts <h2>1. Microsoft</h2> During the second quarter, Citadel Advisors bought 1.87 million shares of Microsoft, increasing its stake in the company by 1,635.75%. Griffin and his team aren't the only ones who have been loading up on the tech leader. There is a reason why Microsoft has crushed broader equities this year and is up 32% since January. Microsoft's financial results back that up. The company's revenue and earnings have been growing at a good clip. In the fourth quarter of its fiscal year 2025, ended on June 30, Microsoft's revenue jumped by 18% year over year to $76.4 billion. Operating income grew even faster, reaching $34.3 billion, a 23% increase compared to the year-ago period. Net income climbed 24% year over year to $27.2 billion. In other words, Microsoft is capitalizing on growth opportunities while keeping costs under control. <div><img src="https://imageproxy.pbkrs.com/https://g.foolcdn.com/image//query-b3A9cmVzaXplJnVybD1odHRwczovL2cuZm9vbGNkbi5jb20vZWRpdG9yaWFsL2ltYWdlcy84MzEyNzcvcGVyc29uLXdvcmtpbmctYXQtYS1kZXNrLmpwZyZ3PTcwMA?x-oss-process=image/auto-orient,1/interlace,1/resize,w_1440,h_1440/quality,q_95/format,jpg" width="700" height="466" original-src="https://imageproxy.pbkrs.com/https://g.foolcdn.com/image//query-b3A9cmVzaXplJnVybD1odHRwczovL2cuZm9vbGNkbi5jb20vZWRpdG9yaWFsL2ltYWdlcy84MzEyNzcvcGVyc29uLXdvcmtpbmctYXQtYS1kZXNrLmpwZyZ3PTcwMA"/>Image source: Getty Images. </div> The tech giant's most important business is currently its cloud unit, a segment that also offers a host of AI-related services and is growing sales faster than the rest of its business. Microsoft is gaining ground on Amazon, the leader in cloud computing. Although Amazon was first to market, Microsoft has been offering its Office 365 productivity tools (and other services) to businesses for a long time. It's hardly a leap for these same companies to opt for a provider they already know and trust for their cloud needs. And the best news is that this is still the early innings of cloud adoption, and for that matter, the AI revolution. As Andy Jassy, Amazon's CEO, said, &#34;85% of the global IT spend is still on-premises.&#34; Despite its massive size, Microsoft is poised for excellent long-term opportunities in cloud computing and AI. Add that to the company's moat from switching costs, its excellent dividend program, and significant cash flow, and Microsoft looks like a no-brainer stock to buy right now. <h2>2. Apple</h2> Citadel Advisors' stake in Apple increased by a whopping 10,715.95% during the second quarter. That seems like an odd move at first glance. Apple has faced significant challenges this year, particularly the threat of tariffs. The company manufactures its products abroad, especially in China. With the Trump administration seeking to impose heavy tariffs on imported goods, the market has been concerned about what this will mean for Apple's business. Apple recently announced that it would increase its domestic investment in manufacturing to $600 billion over the next decade, in an attempt to appease the current administration and avoid tariffs. However, Apple has other issues beyond that. The company's Apple Intelligence -- a suite of AI features and services it has released for its latest devices -- has failed to impress consumers and investors. So, the iPhone maker is behind in this promising industry. It's due to all these factors (and others) that Apple's shares have declined by 5% this year. However, Griffin and his team clearly saw this as an opportunity to load up on the company's shares. In my view, although Apple may struggle for the next few years, the stock remains a solid long-term option. For one, the company's business is still highly profitable. Apple's revenue in the third quarter of its fiscal year 2025, ended June 28, increased by 10% year over year to $94 billion. The company's earnings per share came in at $1.57, representing a 12% increase compared to the year-ago period. Notably, Apple generates a substantial amount of cash. The company's trailing-12-month free cash flow may be down 11.6% year over year, but it remains a considerable $96.2 billion. <img src="https://imageproxy.pbkrs.com/https://media.ycharts.com/charts/b2f211138fdfa2f459043c56d594a4f3.png?x-oss-process=image/auto-orient,1/interlace,1/resize,w_1440,h_1440/quality,q_95/format,jpg" width="720" height="441" original-src="https://imageproxy.pbkrs.com/https://media.ycharts.com/charts/b2f211138fdfa2f459043c56d594a4f3.png"/> AAPL Free Cash Flow data by YCharts Apple can invest a substantial amount of money in R&amp;D efforts that will ultimately yield results, including advancements in AI. The company has been late to market several times, only to create an innovative version of an already existing product and find massive success. That's what it did with the iPhone and several products after that, including its AirPods. The difference is that Apple now has a more valuable brand name than it did then. Apple has an army of loyal customers, an installed base of billions of devices, and a services segment with more than 1 billion paid subscriptions. Even a single highly successful device can have a significant impact on the company's results. Lastly, Apple could find ways to fend off the tariff threat. CEO Tim Cook did so during President Donald Trump's first term. And there is no guarantee that Trump's aggressive trade plans will survive his administration. For all these reasons, the stock remains attractive, particularly for investors willing to hold it over the long term. </div>

Billionaire Ken Griffin, CEO of Citadel Advisors, significantly increased his firm's stakes in Microsoft and Apple during Q2. Citadel bought 1.87 million shares of Microsoft, raising its stake by 1,635.75%, as the company reported strong revenue growth. Apple saw a staggering 10,715.95% increase in Citadel's stake despite facing challenges, including tariffs and competition in AI. Both companies are positioned for long-term growth, with Microsoft excelling in cloud services and Apple maintaining profitability despite recent struggles.

- Ken Griffin's Citadel Advisors significantly increased its stakes in Microsoft and Apple during the second quarter, with Microsoft shares rising by 1,635.75% and Apple by 10,715.95%.  
- Microsoft's strong financial performance, particularly in its cloud unit, positions it well for future growth, while Apple faces challenges but maintains profitability and substantial cash flow.  
- Despite current hurdles, both companies are viewed as solid long-term investment options, with potential for significant returns in the evolving tech landscape.

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Billionaire Ken Griffin Is Loading Up on These 2 Artificial Intelligence (AI) Stocks That Have Increased 88,780% or More