Interested in going into financial service industry, but most firms want at least a 3.5 or higher. How easy is it to get A- or A for econ at Williams?
You will be able to get a 3.5 if that is your primary focus. A lot of econ majors in particular are heavily focused on non-academic pursuits (as opposed to say a math or science major, where the competition is, frankly, a bit tougher in general), so if you are deeply worried about grades, you will be fine. 3.5 is barely above the middle of the curve for a typical econ class, in all events.
You’d be able to do it. And once you did it, matching that with strong undergrad performance across the board would nearly guarantee you one of those coveted spots you desire - Williams is as close to a golden ticket for those jobs as one dare get. Congratulations and good luck!
it’s probably the easiest major to allow you to fake it and make it at Williams (note I didn’t say it was an easy major).