The Fed’s campaign to reduce its $4.4 trillion balance sheet is now taking effect and showing up in the data.

Thursday’s Federal Reserve report on its portfolio holdings shows a near $6 billion decline in its holdings of Treasury securities. It’s the biggest outright weekly decline since 2012.

It’s just the leading edge of more to come as the Fed gradually ramps up its effort to “normalize” its balance sheet. The Fed hasn’t explicitly said what level it’s aiming for, only that it will ramp up its sales of Treasurys and mortgage-backed securities to a point where it eventually is reducing them at a clip of $50 billion a month.

The decline in mortgage-backed securities, which is already taking place, should begin showing up in the data next month.