* Markets to close Monday, reversing earlier decision * Several companies postpone earnings releases * First weather-related closure in 27 years * Last week, Dow off 1.8 pct, S&P off 1.5 pct, Nasdaq off 0.6 pct * Bond market to open until noon ET NEW YORK, Oct 29 (Reuters) - U.S. stock and options markets will be closed on Monday and possibly Tuesday, the exchange operator said, going back on a plan that would have kept electronic trading going on Monday. As Hurricane S