I have a savings account with Ally and an investment account with Wealthfront. I'd like to know how the investment is doing, compared to just leaving the money in my savings account. Ally gives me an APY, while Wealthfront shows me the time- and money-weighted returns. Is there any way to compare these two numbers?
try the formula
=investment_return / (DAYS(TODAY(), date_of_purchase) / 365)
The DAYS() method returns the number of days between two dates and TODAY() will (as you might have guessed) return today's date. By dividing your return by the fraction of a year since you purchased it, this "approximates" an APY.
Keep in mind this function could be extremely misleading if the time since its purchase is small. For context, the 1-day change of the S&P 500 was +0.46% at time of posting, yielding an approximated APY of 167.9% from this formula if purchased yesterday (about three times its best ever year. source: https://fourpillarfreedom.com/heres-how-the-sp-500-has-performed-since-1928/).