The stock market is struggling to take it to the next level. For a third straight day, the S&P 500 traded above its record close — led by retailers and home builders — but fell back to end below it. Since rebounding from losses early in the year, when worries about growth in emerging markets and the US spooked investors, the market now appears at a crossroads. Investors may get a catalyst on Thursday, when the Fed’s chief testifies to Congress. Her comments will be scrutinized for clues about how much an unusually cold winter has affected economic activity, and for confirmation the Fed will maintain its stimulus-trimming schedule.