How does one go about calculating the performance of a portfolio when the portfolio is robo-managed and rebalances often, therefore making tracking every transaction and exact holdings over time a pain. All the software and formulas I've seen assume that you know exactly how many of each share you hold and the stock price of each and you need to enter every buy/sell/dividend-reinvest to keep the calculation accurate.
What I do have is 1) the book value (sum of all deposits - all withdrawals), 2) dates and amounts of human-made deposits/withdrawals and 3) the exact market value of the portfolio that day (this includes reinvested dividends).
I'm looking for some way to calculate MWRR, TWRR and such metrics (or an approximation) without having to enter every movement that the robo-advisor did. I want to update this by hand every quarter or something where I just look at that day's account market value, enter it in some spredsheet/software and get performance metrics up to that day.
Is this possible at all? I tried using a custom "metastock" to represent all the account holdings but I still couldn't figure out how to enter transactions
2020-03-04, deposit $80, auto-invested in 11 different companies 2020-04-01, unknown rebalance of those 11 companies 2020-04-02, auto-reinvest $2 from dividends 2020-05-01, unknown rebalance where 1 of those companies was sold completely, leaving only 10 companies in the portfolio 2020-05-23, deposit $100, auto-invested in 3 different companies 2020-05-31, I see: book value = $180, market value = $195 2020-06-01, unknown rebalance 2020-07-01, unknown rebalance 2020-07-01, auto-reinvest $13 from dividends 2020-11-13, deposit $30, auto-invested in the same 10 companies 2020-12-31, I see: book value = $210, market value = $201 2021-03-01, unknown rebalance 2021-06-12, deposit $100, auto-invested in 8 companies 2021-07-01, I see: book value = $310, market value = $408 2021-07-08, auto-reinvest $13 from dividends 2021-09-01, unknown rebalance 2021-12-31, I see: book value = $310, market value = $453
I would like to calculate annualized and overall performance