As investors are reassessing the rebound in risk assets in March and the hidden worries of the global economic outlook, risk aversion is returning again, and investors embrace security assets.

The yield of Bank of America Global sovereign bond index is now down to 1.3%, the lowest level recorded in nearly 20 years.

Meanwhile, the MSCI global index hit its biggest decline in 2 months, Europe and the United States.

With pressure on both sides, demand for us debt, gold and yen increased, the US dollar fell below the 110 pass against the yen, the first since October 2014.

As global bond yields have continued to record low recently, Bloomberg quoted Hideaki Kuriki, an analyst at Mitsui Sumitomo bond market, said: "this is actually a manifestation of global deflation, and the improvement of the US economy does not drive global economic growth."

Tonight, the Federal Reserve and the European Central Bank will issue a summary of the monetary policy conference this week.

Before these two heavy events, investors remained cautious.

The European Central Bank meeting in March offered a big move to reduce the three interest rate and expand the monthly interest rate.

Purchase amount to 80 billion euro and expand purchase scope, and start TLTRO2.

Yellen, chairman of the Federal Reserve, spoke at the New York Economic Club on Tuesday.

The slowdown in the global economy and the uncertainty of the financial market will make the US economy face more risks. Therefore, the Fed should increase interest rates even more slowly.

The Federal Reserve's monetary policy conference in March kept interest rates unchanged. The dot map shows that officials expect to raise interest rates two times in the year, compared with the four rate hike in December.

The Fed said that the weakness of overseas economy and the dramatic movement of financial markets bring some risks to the economic prospects.