Foreign Ownership Limits and Restricted Share Classes

Some governments restrict how much of a domestic company foreign investors can own, often to protect sectors like banking, media, or telecoms. Rather than turning foreign buyers away entirely, exchanges in countries like Thailand, the Philippines, and Vietnam solve this by splitting a company's stock into two share classes: local shares, restricted to domestic buyers, and "foreign" shares, which carry identical economic rights but are the only ones foreigners may legally hold.

Because both classes represent the same claim on the same company, you'd expect them to trade at the same price. They usually don't. When the foreign quota is close to full, foreign shares trade at a premium — sometimes a large one — simply because demand from foreign investors is chasing a fixed, shrinking supply of eligible stock. Once the quota is completely exhausted, foreign shares can only be bought from an existing foreign holder, cutting off new foreign inflows entirely until someone sells.

Worked example

A Thai bank has a 25% foreign ownership limit. Foreign investors already hold 24.8% of shares outstanding. A large index fund needs to buy more foreign-class stock to match its benchmark weight, but almost no quota room is left. It bids up the foreign share price to 8% above the local share price just to induce an existing foreign holder to sell, since the alternative — waiting for room to open — offers no guarantee of ever filling the order.

This premium is not arbitrage-able in the normal sense: a foreign investor cannot simply buy the cheaper local shares instead, because doing so is against the law. The gap can persist indefinitely and tends to widen exactly when the stock is most attractive to global investors, which is precisely when index funds need it most.