With a little over three months remaining in 2025, now might be a good time to think about making some portfolio adjustments ahead of the new year. Artificial intelligence (AI) is currently a key driver of stock market returns, and we could still be in the early innings of this tech revolution, so investors who lack exposure might want to make some moves.

Purchasing just one or two exchange-traded funds (ETFs) can be the equivalent of buying an entire portfolio of AI stocks. Here’s why the Roundhill Generative AI and Technology ETF (CHAT 1.91%) and the Vanguard Mega Cap Growth ETF (MGK 0.61%) are two great potential candidates.

The case for the Roundhill Generative AI and Technology ETF

The Roundhill ETF invests in companies developing the platforms, infrastructure, and software powering the AI revolution. It holds just 38 stocks, and the fund is actively managed, which means Roundhill’s team of experts regularly adjusts the portfolio based on what they think will generate the best returns.

The top five holdings in the ETF are some of the most dominant companies in the AI industry. They have a combined portfolio weighting of 25.6%, so they heavily influence the overall performance of the ETF:

Data source: Roundhill Investments. Portfolio weightings are accurate as of Sept. 4, 2025, and are subject to change.

Nvidia supplies the most powerful data center chips for AI development. Its Blackwell Ultra architecture for graphics processing units (GPUs) is the gold standard for the latest generation of AI reasoning models, which spend time “thinking” before rendering outputs, and consume significantly more computing capacity than traditional one-shot models as a result.

Alphabet and Microsoft developed their own AI virtual assistants, and they are also two of the world’s largest providers of cloud computing services. They operate data centers filled with chips from suppliers like Nvidia, and rent the computing capacity to businesses that use it to develop AI models. Plus, Microsoft Azure and Google Cloud offer a growing number of ready-made large language models (LLMs) from leading third-party developers, which businesses can use to fast-track their AI software projects.

Oracle is another provider of cloud services, except its data centers are considered to be among the industry’s most cost-effective and most powerful for processing AI workloads. The company believes it can grow its geographic footprint at least tenfold over the long term, which could drive incredible returns for its stock.

Actively managed funds come with higher costs, so the Roundhill ETF has an expense ratio of 0.75%, which is much higher than the 0.07% charged by the Vanguard Mega Cap Growth ETF. In dollar terms, an investment of $100,000 in the Roundhill ETF would incur an annual fee of $750.

However, investors have been well compensated for the relatively high cost, because the ETF has delivered a return of 111% since it was established in May 2023, crushing the 55% return in the benchmark S&P 500 (^GSPC 0.21%) index over the same period.

The case for the Vanguard Mega Cap Growth ETF

The Vanguard Mega Cap Growth ETF is a passive fund, meaning Vanguard’s portfolio managers have limited discretion over its holdings. It’s designed to track the performance of the CRSP U.S. Mega Cap Growth Index, which invests in the top 70% of the cumulative market capitalization of the CRSP U.S. Total Market Index. The CRSP U.S. Total Market Index holds all 3,508 stocks listed on American stock exchanges.

The Vanguard ETF holds just 69 stocks, which highlights the extreme concentration of wealth in the corporate sector. To explain it a different way, just 69 companies represent 70% of the entire value of all 3,508 companies listed on U.S. stock exchanges.

It just so happens that many of America’s largest companies operate in the tech and tech-adjacent industries. In fact, the top five holdings in the Vanguard ETF are among the biggest names in the AI space.

Data source: Vanguard. Portfolio weightings are accurate as of July 31, 2025, and are subject to change.

Apple continues to roll out its Apple Intelligence software, which brings several AI features to iPhones, iPads, and Mac computers. With more than 2.35 billion active devices worldwide, Apple could eventually become the biggest AI touchpoint for consumers on the planet.

Amazon Web Services is larger than both Microsoft Azure and Google Cloud, and it’s firmly focused on AI right now. But Amazon has deployed over 1,000 AI applications across its entire organization, which spans e-commerce, digital advertising, streaming, and more.

The Vanguard ETF has delivered a compound annual return of 13.5% since its inception in 2007, comfortably outpacing the S&P 500, which has grown by an average of 10.4% per year over the same period. But thanks mainly to the proliferation of AI, the ETF has soared by almost 26% annually over the last three years.

Therefore, like the Roundhill Generative AI and Technology ETF, the Vanguard Mega Cap Growth ETF offers investors a simple way to expose their portfolio to the AI boom.