Sivan Whiteley, associate general counsel of Square Inc., helped close a convertible debt offering that is expected to net nearly $390 million in proceeds for the company.

The No. 1 issue that keeps me and my clients up at night is …

Data security. You mess that up in a major way and so much of what you spent years building can be damaged overnight. We're going to look back on this time 10 years from now and it's going to seem like the Wild West in terms of the infrastructure, systems and processes in place to protect data. I think data privacy and security is going to keep a lot of people up at night for some time to come.