Only Haruhiko Kuroda can feel Jerome Powell’s pain.

In March, Federal Reserve Chairman Powell joined his Bank of Japan counterpart in the US$5 trillion club. Eighteen months earlier, Governor Kuroda became the first governor to expand any central bank’s balance sheet beyond that record-breaking level.

Now, the world’s most powerful monetary authority has done the same. And already it’s facing the same stark reality check: running out of ammunition sooner than expected, which in turn presents markets with the possibility of massive fallout.

In recent days, a torrent of analysts and former Fed officials have stepped forward to warn that the US has churned as much monetary stimulus as it possibly can into its economy. That’s worrisome news for Wall Street’s Fed-driven bull market. And for a Dow Jones Industrial Average now down 3.7%, year-to-date.