sentences:  Doidge, Karolyi, and Stulz (2004) show that companies with a cross-listing in the United States have a higher valuation than non-cross-listed corporations, especially for firms with high growth opportunities domiciled in countries with relatively weak investor protection.The premium they find is larger for companies listed at official US stock exchanges (Level II and III ADR programs) than for over-the-counter listings (Level I ADR program) and private placements (Rule 144A ADR's).Doidge, Karolyi, and Stulz (2004) argue that a cross-listing in the United States reduces the extent to which controlling shareholders can engage in expropriation (through "bonding" to the high corporate governance standards in the United States) and thereby increases the firm's ability to take advantage of growth opportunities.