There's been a rapid deterioration in market fundamentals and that means that, even at these much lower prices, global stocks don't look attractive yet.

It's true global growth is still supportive, and so this is unlikely to be the start of a long-lasting bear market. But, one of the other pillars behind the rally has been severely weakened during the past month: liquidity.

Two-year U.S. yields closed Thursday 90 basis points above their finish on Sept. 8. That speed of tightening hasn't been seen since the first half of 2008. And we all know how that year ended.

There's more from this angle: five-year U.S. yields also tightened by more than 90 basis points over the same period. That has severely diminished the net-present value of expected future cash flows from stocks, effectively making them look more expensive on this basis.