Who is a company? If we speak of the men and women of Boeing, say, or Wal-Mart or Market Basket, a supermarket chain in New England, where this question is being posed most emphatically of late, are we referring to the company's employees? Its founders? Its founders' grandchildren, even if they play no role in the company's endeavors? Its shareholders, even if they hold the company's stock just for a few months or, in the case of high-frequency trading, a fraction of a second?