Complex sentence: In Fall 2011, after an entrepreneur expressed his penchant for the program to Andersen, Startup Grind spread to Los Angeles and New York City; by August 2013, the organization had fifty chapters in twenty nations.
Split into simpler sentences: In Fall 2011, after an entrepreneur expressed his penchant for the program to Andersen, Startup Grind spread to Los Angeles and New York City. By August 2013, the organization had fifty chapters in twenty nations.