Why does wifi availability kill 3G/4G Data?

[semi_engineer]

I've noticed that if my GNex sees an available wifi network it will immediately kill my wireless data signal, regardless of whether I connect to that network or not. There are some things that I prefer not to do over a public network, in particular using banking apps. Has anyone else seen this behavior? If so, is there a way to alter it in settings?

[NexusMan21]

Turn off your Wifi when you don't intend to use it. Your phone won't be able to see any Wifi networks, if it is not on.

[semi_engineer]

Thanks, NexusMan21. That is exactly what I do. I was just wondering if there was a settings option to prevent this behavior without disabling the wifi. I understand that it is a data-saving feature and appreciate it for that.