Companies are getting very good at collecting lots of information about you and your habits. The catch-all term is “big data” — and there’s a running debate about what companies should and should not be allowed to do with all this info.

At a big computer security conference in San Francisco last week, a key theme was not what companies can and should do with big data, but what crooks might do with it if they hacked in.

Chester Wisniewski, a computer security expert at Sophos, joins Marketplace Tech host David Brancaccio to discuss steps companies are taking to shore up customer data.