Mario Gabelli Stock Portfolio: Top 5 Stock Picks

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1. Mueller Industries, Inc. (NYSE:MLI)

GAMCO Investors’ Stake: $214 Million

Mueller Industries, Inc. (NYSE:MLI) has consistently featured in the 13F portfolio of GAMCO Investors since the third quarter of 2012. Back then, this position comprised 644,000 shares. The fund steadily built up this stake in the coming quarters, growing it to 8.7 million shares by the second quarter of 2018. Thereafter, it started trimming this holding. Filings for the fourth quarter of 2025 show that the fund owned nearly 1.9 million shares in the firm, down close to 15% compared to filings for the previous quarter.

Hedge funds are drawn to Mueller Industries, Inc. (NYSE:MLI) due to its high-quality financial metrics, its status as a critical supplier for the white-hot data center market, and significant shareholder value initiatives. As of early 2026, MLI boasts a Return on Equity of 25%, which is more than double the industry average of 11%. For every $1 of shareholders’ equity, the company generates $0.25 in profit. While Mueller is a veteran industrial company, manufacturing copper and brass components, it is currently benefiting from modern tech trends. Mueller’s plumbing and HVACR (heating, ventilation, air conditioning, and refrigeration) products are essential for the cooling systems required in massive AI data centers. In mid-February 2026, Mueller announced a 40% increase in its quarterly dividend, to $0.35 per share.

While we acknowledge the potential of MLI to grow, our conviction lies in the belief that some AI stocks hold greater promise for delivering higher returns and have limited downside risk. If you are looking for an AI stock that is more promising than MLI and that has 100x upside potential, check out our report about the cheapest AI stock.

READ NEXT: 12 Best Stocks to Buy According to Billionaire David Abrams and 15 Best Stocks to Buy According to Billionaire Seth Klarman.

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