TY - JOUR T1 - A Note on the Valuation of American Option JO - Journal of Partial Differential Equations VL - 1 SP - 29 EP - 36 PY - 2003 DA - 2003/02 SN - 16 DO - http://doi.org/ UR - https://global-sci.org/intro/article_detail/jpde/5403.html KW - American option KW - Free boundary problems AB - American options give holder a right to exercise it at any time at will, the holder should to make the exercise policy in such a way that the expected payoff from the option will be maximized. In this note we prove that it is equivalent to a fact which makes the option value and option delta continuous.