Multi listed or cross-listed shares, by contrast, are technically the same financial instrument. Fungibility is a concern across markets. For example, shares of IBM cannot be purchased on NYSE and sold, same-day, on the London Stock Exchange, even though IBM is cross listed in both markets. There is a re-registration process that must occur to move the number of outstanding shares from one jurisdiction to the other. This is primarily due to market inefficiencies and structures required to maintain the integrity of registered shares within specific jurisdictions (typically regulatory driven).