When the Deepwater Horizon rig exploded and sank on April 20, BP's stock plummeted, which hurt investors as well as BP employees with 401(k) plans, according to CBS MoneyWatch.
SEC filings indicate that almost 30 percent of BP's 401(k) plan was invested in BP stock, which caused many people to lose a substantial part of their retirement income. It is estimated that the oil company's stock has lost more than $1 billion in value since April 20.
This drastic reduction in value of pension plans has caused a number of parties to file lawsuits against BP, including the state of New York, which lost more than $30 million from its pension fund because of the drop in BP stock, according to the New York Daily News.
The explosion of the Deepwater Horizon rig took the lives of 11 workers.