There are many reasons for the intercompany mobility of employees (wage differential, career prospects, etc), with the closure of companies being one of the main factors: in the United States of America, for example, one in four job losses is due to company closure. Since it is the smallest companies that close down the most often, the average length of service is shorter for employees of small companies than for those of larger companies. This is also an important factor in France: between 1985-1999, one in four people employed in companies with less than 20 employees who moved jobs were forced to do so due to the closure of their company. If we focus on companies that did not close during this period, people employed in companies with less than 20 employees stay in their company for longer than people employed in the largest companies. This «forced» mobility due to company closure generally affects employees of small companies more than employees of large companies, and employees in companies that belong to a group more than employees of independent companies; forced mobility tends to diminish as length of service increases. The working class is the most at risk of this forced mobility. The construction industry is the most affected due to the high turnover of construction companies. Finally, a person's length of service in a company at the time they leave is, all things being equal, the main factor for this mobility, whether it is forced or not.