Fixed-income investors pulled billions of dollars out of speculative-grade corporate bond-related ETF as the rising rates sparked credit risk concerns.

Investors yanked more than $6 billion out of junk bonds in the past week, the largest outflows for the asset category since a previous bout of market volatility back in February, the Financial Times reports.

For example, the iShares iBoxx $ High Yield Corp Bd ETF (NYSEArca: HYG) was the most hated ETF play of the past week as investors pulled $2.8 billion from the fund, and the SPDR Barclays High Yield Bond ETF (NYSEArca: JNK) experienced $1.3 billion in outflows as well, according to XTF data.

John McClain, a portfolio manager at Diamond Hill Capital Management, argued that the capital flows were due to “a risk-off attitude” that gripped global financial markets. Riskier assets like speculative-grade debt have sold off after yields on benchmark government debt hit a seven-year high, which added to concerns over extended valuations.

While some may still like the high-yield segment, David Albrycht, chief investment officer at Newfleet Asset Management, warned that “valuations are full”.