Optimists take the view that, like a skilled pilot, Fed chairwoman Janet Yellen will be able to bring the size of the balance sheet down smoothly and steadily without hitting too much turbulence.
Pessimists, however, believe the pilot is flying blindly through dense clouds with a faulty radar and constant risk of storms, making the policy normalisation process particularly risky.
"For me the new thing to look out for is what they do to the portfolio," says Robert Michele, chief investment officer at JPMorgan Asset Management. "We know about moving the [interest rate] corridor. What we should be worried about is what they do with the balance sheet."
The Fed's strategy for reducing its bloated balance sheet has evolved over time, but in September policy makers said the Fed will cease or start phasing out reinvestments only after it first begins increasing short-term interest rates. The balance sheet would shrink in a "gradual and predictable manner", but the details were left unclear — as well as the timing, which will depend on how economic and financial conditions evolve.
One market concern is that allowing assets to roll off automatically as they mature could lead to a jagged path of balance-sheet reduction. BlackRock's Investment Institute pointed out in a recent report that a third of the Fed's entire Treasury portfolio, about $785bn, comes due by the end of 2018. Allowing the balance sheet to deflate that quickly could spook markets.'