The High Yield Corporate Fund, managed by Boston-based Wellington Management Co., received $2 billion from clients over the past six months, the Valley Forge, Pennsylvania-based company said Thursday in a statement. It remains open to existing shareholders and some Vanguard clients.

Vanguard joins T. Rowe Price Group Inc. in shutting a junk- debt fund after investors funneled $23.1 billion into the securities this year, 48 percent more than all of 2011, JPMorgan Chase & Co. strategists said in a May 18 report. The bonds have lost 1.3 percent this month as concern mounts that Greece’s political crisis will cause it to exit Europe’s common currency, sending the euro region into a recession and disrupting the financial system.

“It’s a responsible step for a high-yield fund to stop taking in money if it can’t continue to invest it without deviating from its established credit-quality standards,” Martin Fridson, New York-based global credit strategist at BNP Paribas Investment Partners, said in an e-mail. “I do think it’s a case of too much inflow chasing too little issuance.”

Rates Near Zero

While investors withdrew $689 million from high-yield bond funds last week, largely because of $918 million pulled from exchange-traded funds, they poured $229 million into actively managed accounts that buy the notes, JPMorgan analysts led by Peter Acciavatti wrote in the note last week. Investors are attracted to the speculative-grade corporate securities as the Federal Reserve has kept rates near zero since December 2008.

“We are taking these proactive steps to preserve the ability of the advisor to manage the fund effectively and protect the interests of existing shareholders,” William McNabb, Vanguard’s chief executive officer, said in the statement. The company manages $1.84 trillion in U.S. mutual fund assets, it said in the statement.

T. Rowe Price said it was closing certain classes of its $9.4 billion High Yield Fund and $2.6 billion Institutional High Yield Fund in a May 1 statement. It last shuttered the funds in February 2004 and reopened them three years later.

High-yield funds are holding almost twice the percentage of their assets in cash now than in 2011, up to 6 percent versus 3 percent a year ago, according to the JPMorgan analysts.

If money continues to pour in, “it could eventually strain our ability to invest efficiently,” Mark Vaselkiv, head of T. Rowe Price’s taxable high-yield bond team, said in the statement.