The last time we looked at this issue, the Einsteins who write for yahoo.com hadn’t decided how to form a possessive of a name that ended in the letter S. You’d think by now they’d come to a decision. But no. Sometimes they just add an apostrophe, following the Associated Press style:
and sometimes they add an apostrophe and an S:
And all the time they just look like amateurs working for a media giant that doesn’t even have a house style.