Someone in my ward is getting divorced and it turns out that one of the spouses had a "substantial" amount of money in an investment account that the other spouse was never made aware of.*

Just for curiosity's sake, I've wondered if this is a common thing. Nothing for tax evasion or anything, just gray money to spend on yourself without your spouse knowing. Maybe you got tired of your spouse spending all the communal money on himself or herself. Or maybe you needed your spouse to think that she/he needed to save more money.

*Information derived from my wife being in the RS presidency.