After months of warnings from market watchers, the Chinese solar stock, Hanergy Thin Film Power Group, started to set on a pretty powerful year so far. MarketsMuse blog update profiles the effects this Chinese stock has had on the Guggenheim ETF, which MarketsMuse has profiled before. This MarketsMuse update is courtesy of MarketWatch’s Victor Reklaitis and his article, “China solar stock implosion a reminder to look under ETF’s hood“

Many market watchers have warned this year about a highflying Chinese solar stock—Hanergy Thin Film Power Group—and its leading role in popular ways to bet on solar stocks like one Guggenheim ETF.

On Wednesday, Hanergy’s 0566, -46.95% aerial routine ended with a crash, as one Wall Street Journal headline put it. And the Hong Kong-listed stock’s dive after a meteoric rise was helping to take down the Guggenheim Solar ETF TAN, -7.79%

So what’s the takeaway?

“Investors should take care to look under the hood of the ETFs in order to understand what exposure they are possibly buying into,” said Markit analyst Relte Schutte in an email to MarketWatch on Tuesday about the solar ETF and Hanergy.

Schutte had noted in a May 6 commentary that about half of the Guggenheim ETF’s year-to-date jump of 40% was due to Hanergy’s surge of 157%. The ETF was about 12% exposed to Hanergy as of Tuesday, before its big plunge, making it the largest stock in that fund. Hanergy also has been the biggest holding in two rival ETFs, the Market Vectors Solar Energy ETF KWT, -6.88% and iShares Global Clean Energy ETF ICLN, -2.57%

To continue reading about the implications the crash the Hanergy Stock has had on the solar ETFs, click here.