Forming the possessive of a name ending in S can be problematic. Do you add an apostrophe and an S? Just an apostrophe?
It’s a matter of house style. If you follow the Associated Press style, simply add an apostrophe (like Hanks’). Other authorities suggest adding an apostrophe and an S (like Phelps’s). If you follow the Yahoo! style, do whatever the hell you want. Nobody cares: