The rules vary by company. Getty Images By Kimberly Lankford, Contributing Editor October 4, 2018From Kiplinger's Personal Finance I’ve arranged for my IRA administrator to take out RMDs for me automatically, but how does it determine which investments to sell? - G.C., Santa Clara, Calif.SEE ALSO: 5 Best Actively Managed Vanguard Funds The rules vary by company. At Fidelity, you can have the money withdrawn proportionately from each of your IRA investments (the most common option). Or you can elect a fixed percentage from a few investments or have 100% taken from cash. Vanguard has similar options. Charles Schwab takes automatic RMDs only from cash, and the firm sends an alert two weeks beforehand in case you need to sell shares to raise the money. Got a question? Ask Kim at email@example.com.