Size doesn’t matter for one exchange-traded fund that’s beating the competition.

A fund with just $29 million was the star performer in the $4 trillion U.S. market last month, returning more than any other unleveraged ETF, data compiled by Bloomberg show. The Virtus LifeSci Biotech Clinical Trials fund, which trades under the ticker BBC, gained 22%, beating more than 1,970 rivals.

The fund benefited from a busy month for biotech companies. While Novartis’s $9.7 billion takeover of Medicines Co. boosted overall sentiment, stakes in ChemoCentryx Inc. and Karyopharm Therapeutics Inc. helped BBC outperform. ChemoCentry’s shares soared on positive data regarding a drug to treat an inflammation disease, while Karyopharm reported better-than-expected sales.

“Fundamentals in biotech stay strong and insulated from trade discussions making it an appealing place to invest,” said Maury Raycroft, an analyst at Jefferies. Clinical trials, M&A activity, and a favorable regulatory environment are all helping to foster a positive outlook, he said.

BBC’s returns exceeded the S&P 500 Index by 18% last month.

Eight of November’s top 10 performing ETFs focused on biotechnology, or a related theme. The $4.3 billion SPDR S&P Biotech ETF was the biggest of these funds, and returned almost 15%.