It's certainly possible that they may be more secure than a lot of smaller sites, although that's not guaranteed - social media sites are fairly likely to be more interested in agility than robust security.
What is pretty much guaranteed is that there's more people trying to hack Facebook/Twitter security than most smaller sites.
> What is pretty much guaranteed is that there's more people trying to hack Facebook/Twitter security than most smaller sites.
That, and the fact that they're still around means exactly that it is guaranteed they are more secure than most of the smaller sites. Being a big and valuable target to hit, they can only adapt or die.
What is pretty much guaranteed is that there's more people trying to hack Facebook/Twitter security than most smaller sites.