Early exercise of American calls on non-dividend stocks is never optimal.

Evidence

Merton (ibid., pp. 143-144) showed, under quite general conditions, that the early exercise of an American call on a non-dividend-bearing stock is never optimal, so its theoretical value is equal to that of a European call. — Donald MacKenzie, An Engine, Not a Camera, 1559

Categorization

• DEFINE: Clarifies the key theoretical equivalence between American and European call values under specified conditions.