You work for one of the approximately 667,000 construction companies in the United States. You may or may not be unionized, but chances are you "follow the cranes," moving from job to job in pursuit of the best opportunities.
That's why multi-employer plans are widespread in this dispersed and partially seasonal industry. The industry as a whole is healthy, but individual, often-leveraged companies come and go week by week, season by season - which can affect your pension. So you should keep a close eye on your retirement nest egg.
