San Francisco Business Times: Twitter abandoned plans at the 11th hour last week for a big expansion into Uber and Square’s headquarters at 1455 Market Street in San Francisco, potentially due to a hiring slowdown. Before putting U.S. expansion plans on hold, the social networking company had nearly finalized a deal with 1455 Market landlord Hudson Pacific Properties to add about 100,000 square feet of former Bank of America space a block away from its current Market Street headquarters.