It happened so quickly.

While analysts and economists had long debated the efficacy ofquantitative easing — the central bank bond purchase programsaimed at lowering borrowing costs to stimulate the economy andstoke inflation — the narrative surrounding such efforts is rapidlyshifting. In recent months, there's been a growing recognitionof the limits and downsides to this particular form of monetaryeasing, underscored by the Bank of Japan's policy changes announced onWednesday.

Some 15 years after first experimenting with QE, the BOJannounced that it intends to shift the focus of its policyframework to better finesse borrowing costs by, ineffect, anchoring longer-term rates higher, and moving away from arigid target for expanding the money supply. While marketparticipants expect the central bank to further expand bondpurchases and take the rate on a portion of bank balances deeperinto negative territory in upcoming meetings, the BOJ's move is arecognition that its daring strategy to dramatically expand themoney supply to fight deflation has delivered a blow to thefinancial sector's profitability.