By cushioning the first-round economic impact of the financial stress, we hoped also to minimize the risks of a so-called adverse feedback loop in which economic weakness exacerbates financial stress, which, in turn, further damages economic prospects.

FORBES: Reducing Systemic Risk

Tighter monetary policy would then have made an adverse feedback loop more likely: The greater uncertainty about asset values would raise credit spreads, causing economic activity to contract further, thereby creating more uncertainty, making the financial crisis worse, causing the economic activity to contract further, and so on.

WSJ: The Fed Still Has Plenty of Ammunition