Every one of the current pronunciation dictionaries agrees that the stress in the word inexorable is on the second syllable. On Monday this week, in the Radio 4 programme charting the history of Britain in numbers, Professor Jane Humphries, Professor of Economic History, All Souls, Oxford, clearly said /ÉªnekËˆsÉ’rÉ™bÉ™l/. It might have been less surprising if the stressed vowel had been the longer /É”Ë/, as in adorable, deplorable, ignorable, restorable. Google lists 29 words ending in –orable, and not one, so far as I can see, ends in /-É’rÉ™bÉ™l/.
Perhaps Professor Humphries is setting a new trend. Time will tell.