I live near an EBay headquarters in silicon valley. There certainly are a lot of 30- people with money in the area. Two local small towns have completely transformed. One now has regularly scheduled town meetings on how to fold diapers or some such. Real estate prices have skyrocketed, even on the silicon valley scale of things.
So I agree that such people are a decent sized ($)customer/reader base...
But I think Yahoo Finance is where most people go to look at the daily charts, and company profiles, etc.. So I hope these tmblr postings get reflected onto the Yahoo Finance headlines. I guess it would be surprising if they did not get listed there.
There is Goggle Finance, and the NASDAQ website itself, and those are better for some things, but I think the primary traffic is at Yahoo Finance.