Recent weakness in high-yield bond exchange traded funds is a worrying sign for U.S. stocks. The junk bond ETFs are testing the 200-day exponential moving average after a rough start to the second quarter, while one technical analyst sees a bearish pattern forming.

Some investors keep a close eye on junk bond ETFs such as iShares iBoxx High Yield Corporate Bond (NYSEArca: HYG) and SPDR Barclays High Yield Bond (NYSEArca: JNK) as a sentiment indicator for how comfortable investors are with taking on risk. [What High-Yield Bond ETFs are Saying About Stocks]

The high-yield funds are testing the key 200-day moving average for the first time this year.

“As high-yield credit is highly correlated with equities, it’s hardly surprising that the asset class has rallied sharply since fall lows, taking part in the strong rebound in stocks and other risky assets,” said Russ Koesterich, iShares global chief investment strategist, in a recent commentary.

Junk bond ETFs have been extremely popular with investors exploring other asset classes in their search for yield.