I have sought the answer in both the TSP website as well as FINRED website. I actually called TSP customer support twice and the two employees I spoke to me they could not answer this question.
What do TSP fund performance percentages actually mean? For example, in 2021 TSP reports the C fund growing by 15.63%, however if you look through each month you don’t see numbers that indicate that’s the average growth for the year. For this I am led to believe that the percentage represents an accumulation of each month’s growth (or decline). But, when I add them all up I get a different number. For C Fund 2021 I am seeing 26.02% when I add each month up, whereas TSP is reporting the fund growth as 28.68%.
Am I missing something? Does my question make sense?