This paper provides a detailed analysis of changes in insurers' lowest cost silver Marketplace premiums between 2014 and 2015 in multiple regions in 17 states plus the District of Columbia. In most markets studied, consumers will be able to buy a silver plan at a lower cost than in 2014 or at a small increase (less than 5%). Because competitive dynamics frequently led to different carriers offering the lowest cost silver plan in 2015 than in 2014, consumers seeking the lowest premium may have to switch insurers.