Investors in funds worldwide pulled $12 billion out of stock mutual funds in the week ended Wednesday on fears that reduced Federal Reserve bond purchases could hurt stock prices, data from a Bank of America Merrill Lynch Global Research report showed on Friday.

The big outflows in the week ended December 18 from stock mutual funds, which are often purchased by retail investors, came after investors pulled $4.5 billion from the funds the previous week. Stock ETFs, meanwhile, attracted $9 billion in new cash from investors over the latest weekly period.

Retail investors were bracing for a cutback in the Fed's $85 billion in monthly bond-buying at the end of its two-day meeting on December 17-18 and decided to "take some money off the table," said Michael Jones, chief investment officer of RiverFront Investment Group.

The outflows from stock mutual funds and inflows into stock ETFs resulted in net outflows of $3.4 billion from stock funds, according to the report, which also cited data from fund-tracking firm EPFR Global. The outflows reversed net inflows of $1.4 billion into the funds the previous week.

Demand for emerging market stock funds was particularly hard-hit. Investors withdrew $3.1 billion from the funds over the weekly period, marking the eighth straight week of outflows.

Emerging market countries, especially those with large budget deficits such as Brazil and Indonesia, are most vulnerable to a cutback in the Fed's bond-buying, RiverFront's Jones said.

Fed stimulus has benefited emerging market nations this year by spurring demand for the countries' assets from yield-hungry investors. With regard to the more fragile emerging market economies, the scaling back of the Fed's aggressive asset purchases is a "knife at their throat," Jones said.

The Fed's monthly purchases of Treasuries and agency mortgages have helped boost the benchmark Standard & Poor's 500 stock index nearly 27 percent this year. The purchases have kept bond yields low, leading investors to seek higher income in stocks and other riskier securities.

The purchases have also driven demand for stock funds, which have attracted net inflows of $244 billion so far this year, the largest annual inflows since 2004, according to the Bank of America Merrill Lynch report.

The central bank surprised investors on Wednesday by announcing a cut of $10 billion a month to its monthly bond purchases, reducing them to $75 billion a month.

Stocks on Wall Street rallied more than 1 percent on the surprise. The S&P 500 rose 1.6 percent over the reporting period.

Investors also pulled a hefty $9.1 billion out of bond funds over the latest week, marking the largest weekly outflows since June and the third straight week of outflows from the funds, the report showed.

The yield on the benchmark 10-year U.S. Treasury note rose five basis points to 2.89 percent over the weekly period. Bond yields move inversely to their prices. Fears that a pullback in the Fed's easy money policies could hurt bond prices triggered the selling pressure over the week.

Investors showed their aversion to bond funds overall by pulling cash out of funds that hold both lower-quality and higher-quality rated debt.

Riskier high-yield junk bond funds had outflows of $900 million, marking their largest outflows since August, while safer investment-grade bond funds had outflows of $2.2 billion, their largest in seven weeks.

Money market funds, which are low-risk vehicles that typically invest in short-term securities, had sizeable outflows of $35 billion after two straight weeks of inflows. Such funds are viewed as a safe place to park cash.

Investors have pulled $92 billion out of money market funds this year, the fifth straight year of withdrawals, according to the Bank of America Merrill Lynch report.

Money market funds took a hit in mid-October when political brinkmanship ahead of a crucial deadline to raise the nation's $16.7 trillion debt ceiling resulted in the largest weekly outflows from the funds since August 2011.

The funds often hold short-dated U.S. government debt and were viewed as particularly vulnerable to a potential U.S. default on its debt.

Investors pulled $1.6 billion from commodities funds over the latest weekly reporting period, marking the biggest weekly outflows from the funds since July. The funds mainly invest in physical gold and other precious metals.

Analysts have said investors have soured on gold this year as a result of falling prices on the metal. Investors have pulled $41 billion out of commodities funds this year, marking the first annual withdrawals on record, according to the report.