American Airlines will be removed from the S&P 500 index, effective Sept. 23.
The change is part of the large-cap index's quarterly adjustment process and reflects American's overall loss of market capitalization over time, relative to other large public companies.
American will become part of S&P's MidCap 400 index.
American stock is currently trading at just over $11 per share, down more than 62% from five years ago.
American's market capitalization is currently $7.35 billion, down from a peak of more than $37 billion in December 2014, according to the ranking site Companies Market Cap.
Delta, Southwest and United remain in the S&P 500.