This column was originally published on RealMoney on Oct. 5 at 1:59 p.m. EDT. It's being republished as a bonus for TheStreet.com readers.There has been a sudden weakening of the stock market over the past few days. It appears to be related to worries about interest rates, which have escalated over the past week following numerous warnings from Federal Reserve officials about the likelihood of continued rate increases. This is apparent in the behavior of various sectors of the stock market and other asset classes. Also contributing to the slide was Wednesday's release of the Institute for Supply Management's monthly index for the nonmanufacturing sector. The index, which was much weaker than expected, suggests that the recent signs of resilience in the economy were largely confined to manufacturing -- an unfavorable mix because of its implications for continued job growth and the chances for a sustained expansion (more on this later).