The equities market and stock exchange traded funds ended up paring their best monthly rally since February over the last days of May.

Over May, the Dow Jones Industrial Average rose 0.8%, the Nasdaq Composite increased 2.1% and the S&P 500 gained 1.0%.

The best performing non-leveraged exchange traded products over the past month include the Market Vectors ChinaAMC SME-ChiNext ETF (NYSEArca: CNXT) up 24.4%, Deutsche X-trackers Harvest CSI 300 China A-Shares Fund (NYSEArca: ASHR) up 19.9% and ALPS Medical Breakthroughs ETF (NYSEArca: SBIO) up 12.8%.

Despite falling off in the last few days, ETFs holdings China A-shares, the stocks trading on mainland exchanges in Shanghai and Shenzhen, surged in May after index provider FTSE Russell said it will transition A-shares into global benchmarks.

Moreover, MSCI is expected to make an announcement regarding the inclusion of A-shares in its global benchmarks on June 9. FTSE is creating two transition indexes to ease the move of A-shares into traditional benchmarks. [China ETFs Surge After FTSE Move to Include A-Shares in Global Indexes]

Meanwhile, SBIO, which focuses on small- and mid-cap companies that have one or more drugs in either Phase II or Phase III U.S. FDA clinical trials, is enjoying strong growth from new medical breakthroughs and greater merger and acquisition activity in the healthcare space. [More Biotech Deal-Making Lifts a few ETFs]

The worst performing non-leveraged exchange traded products over the past month include the C-Tracks on Citi Volatility Index ETN (NYSEArca: CVOL) down 14.5%, Global X Brazil Financials ETF (NYSEArca: BRAF) down 12.9% and Guggenheim Solar ETF (NYSEArca: TAN) down 12.7%.

The U.S. stock market experienced a relatively uneventful May, with volatility relatively subdued and lethargic trading.