All three major indexes lost 1 percent or more in the last week. Trading has been volatile since late May as traders try to figure out when the Fed will dial back its support for the economy. This week was no different: The Dow fell a total of 243 points on Tuesday and Wednesday then jumped 180 points Thursday. The Fed buys $85 billion in bonds each month to help keep interest rates low. The aim is to encourage borrowing, spending, and investing. Some investors worry that long-term interest rates could spike when the Fed pulls back, raising borrowing costs and threatening the economic recovery. Fed policy makers meet Tuesday.