Yeah you're right. Although, how bad would "S3 is deleted worldwide" be? Or "RDS is down for the foreseeable future"? So IDK... The other problem with them is how big they are, so you can't take proportional weights in them, which messes with risk a bit. I think this is a crap strategy but an interesting idea. As others said, the sentiment scanning probably has a better shot, and you pay the huge spread trading outside RTH.