Redemptions from high-yield bond funds, spurred by Treasury yields at the highest in almost two years, threaten to derail stable credit conditions for the riskiest U.S. companies, according to Moody’s Investors Service.

The credit grader’s list of companies rated B3 with a “negative” outlook and lower rose to 160 as of June 1 from a post-recession low of 146 three months earlier, a research report shows. U.S. 10-year Treasury yields climbed to 2.6 percent Tuesday, the highest close since August 2011, amid speculation the Federal Reserve will trim its $85 billion monthly bond-buying program later this year.

Rising yields and fund redemptions may drain the market liquidity that has bolstered corporate balance sheets and lowered default risk, according to Moody’s analysts led by David Keisman. U.S. junk-rated debt has fallen 3.6 percent in June, poised for its worst monthly loss since September 2011, Bank of America Merrill Lynch data show.

“What was great about the Fed injecting those trillions of dollars was that corporations took advantage of it to lower coupons and push out maturities,” Keisman, who is based in New York, said in a telephone interview. “If liquidity goes away, when it comes time for refunding, they won’t be able to, and that will drive a default cycle.”

U.S. high-yield bond funds have lost 3 percent of their assets through net outflows this year, according to a June 20 research note from Bank of America Merrill Lynch. Dollar- denominated offerings of speculative-grade bonds reached $2.4 billion in the week ended June 21, compared with the 2013 weekly average of $8.2 billion, Bloomberg data show.

Liquidity Stress

Investors are ignoring a credit backdrop still showing that few U.S. speculative-grade companies face liquidity problems or risk violating debt covenants, Keisman said. Moody’s list of the riskiest junk-rated companies is still 45 percent smaller than its peak of 289 reached during the second quarter of 2009.

The credit-grader’s liquidity-stress index, which rises as companies find financing more difficult to obtain and falls as their ability to manage cash needs improves, reached 3.3 percent as of the middle of June, below the 7.3 percent average since 2002, Moody’s data show. The U.S. speculative-grade default rate will reach 2.4 percent by year-end, down from 2.9 percent in May, according to the report.

“The fundamentals are maybe ticking up slightly, but they’re mostly just staying the same,” Keisman said. “And whenever the market moves in one direction and the fundamentals stay in the other, that’s when things get interesting.”