Historical factor returns — net of changes in valuation levels — are much lower than recent performance suggests. (researchaffiliates.com)
These large bubbles and crashes in the absence of significant changes in valuation cast doubt on the assumption of efficient markets that incorporate all public information accurately. (en.wikipedia.org)
So I think the backup is much more a function of the broad changes in valuation, changes in the risk markets, as opposed to any early warning signs of credit deterioration. (global.beyondbullsandbears.com)