This paper uses China’s Split-Share Structure Reform to study the slope of long-term demand curves. The reform increased local A-share float but did not affect foreign B-share float. Across firms, larger increases in A-share float lead to larger decreases in A-share price relative to B-share price, even up to around 10 years after the reform, suggesting that demand curves slope down in the long run. Larger increases in float also lead to larger decreases in turnover and volatility, and demand curves are steeper when the divergence of opinion is greater, consistent with the theory modeling investors with heterogeneous beliefs.