The Bank of Japan held off on expanding monetary stimulus, as Governor Haruhiko Kuroda and his colleagues opted to take more time to assess the impact of negative interest rates.

The move comes as a surprise to the slight majority of economists surveyed by Bloomberg who had projected some action from the central bank in response to a strengthening in the yen that has cast a shadow over prospects for higher wages and investment. The currency rallied against the dollar immediately after the decision while stocks in Tokyo tumbled.

Policy makers are betting that their success in bringing down borrowing costs since unveiling the negative-rate strategy in January will generate an acceleration in lending. They left unchanged three key easing tools -- the 80 trillion yen ($732 billion) target for expanding the monetary base, mostly through government-bond purchases, the 0.1 percent negative rate on a portion of the cash banks park at the BOJ, and a program to buy riskier assets including stocks. Separately, they postponed their time frame for reaching a 2 percent inflation target, to sometime in fiscal 2017, for the fourth delay in about a year.

“Kuroda wanted to make it clear the BOJ won’t make monetary policy driven by market demands. It’s too early to make another move after implementing the negative rate a couple of months ago,” said Kyohei Morita, chief Japan economist at Barclays Plc. “The important message is that the BOJ will be data-dependent and I expect they will bolster stimulus in July as they review the outlook of inflation.”