why is my calculated MTD return different that what is in my IFT history profile?

my calculations show that my MTD is : +1.32%

IFT history profile shows: +1.24%

small difference but figured my spreadsheet should match up to what this site shows. below is my breakdown for this month:

6/30 - 100% G (+0.01%)
7/1 - IFT to 100% I (finished day 100% in G, thus (+0.01%)
7/2 - 100% I (+0.03%)
7/6 - 100% I (-1.97%)
7/7 - 100% I (-0.50%)
7/8 - 100% I (-1.71%)
7/9 - 100% I (+2.06%)
7/10 - 100% I (+1.97%)
7/13 - 100% I (+0.58%)
7/14 - 100% I (+0.81%)
7/15 - 100% I (+0.03%)

I have verified and re-verified all my gains and losses numerous times now.

I am getting +1.33% MTD by adding all my gains and losses for this month together.

0.01+0.01+0.03-1.97-0.50-1.71+2.06+1.97+0.58+0.81+0.03 = 1.32%.

Why is my IFT profile off by 0.08 (%) ?

Thanks in advance!

You can't just add up the daily percentages. Those percentages are % change of one day... so [(Today's Price) - (Yesterday's Price)] / (Yesterday's Price)

MTD would be [(Today's Price) - (Month start price)] / (Month start price). Because the denominators are not equivalent, you can not just add up the daily % changes.

thank you for the information! I will update my personal spread sheets accordingly

in order for me to get the 1.24% MTD I used your second equation (7/15 I fund close price - 7/1 I fund close price) / (7/1 I fund close price) plus the 6/30 G fund close price percent change. I used the 7/1 close price of the I fund since that is when I did my 100% IFT

so is it correct to assume that when calculating MTD when IFTs are made that the percent change of different funds for that specific month are cumulative?

I guess the clearer question now is how is "2015 return" calculated taking into account % changes with IFTs?

Quote:

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Originally Posted by brobin10

I guess the clearer question now is how is "2015 return" calculated taking into account % changes with IFTs?

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Spreadsheets such as our AutoTracker usually maintain an internal 'hidden' balance for each participant. The IFT's throughout the year are applied to this balance. This is how it can keep track of your Monthly %'s even when you are in two or more different funds in one month.

Your yearly/monthly/etc. % would be the same formulas k0n has given you, but using your beginning hidden balance and your ending hidden balance, instead of using the starting and ending fund prices. The problem here is that you don't know the hidden balances.

In this case, you could build such a sheet yourself and plug in the IFT's; or, I believe Tom has some links on this site where you can download a tracker spreadsheet. I'll look and edit this post if I find it.

EDIT:
Here's the link, hope it helps:
TSP Calculator - Thrift Savings Plan

thanks again for the info....I was starting to wonder if there was something I was missing with all of this and I guess its the "hidden balance"

I saw those spread sheets when searching around but wasn't sure how they worked exactly.....I will try them out and see what I can figure out!

Quote:

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Originally Posted by brobin10

thanks again for the info....I was starting to wonder if there was something I was missing with all of this and I guess its the "hidden balance"

I saw those spread sheets when searching around but wasn't sure how they worked exactly.....I will try them out and see what I can figure out!

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Yep, don't think it can be done without some sort of 'balance' to keep track of things.

I've never used the worksheets, but maybe others may have and hopefully, can help you out if you need it later on.

Good Luck!

Quote:

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Originally Posted by brobin10

so is it correct to assume that when calculating MTD when IFTs are made that the percent change of different funds for that specific month are cumulative?

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userque is correct, therefore the percentages would not be cumulative.

... although when you are talking about 1 or 2 IFTs in a month, and you are only looking at that month... its probably close enough for estimating. But if you are trying to forever in the future match the tracker... you'd have to do what userque described and use an actual fund balance. It shouldn't matter what you start with... whether its $1 or $1000000, the percentages should work out the same. If I was going to do it... I'd probably use either $1 or $100.

Thanks for helping, everyone!

Here is the calculation I use in the spreadsheet to compound a start return and a new daily return…

total = (100 * ((1 + (start_return)) * (1+ (daily_return)))-100) / 100

Forget math explanation.

It's magic.

the Autotracker does it all by magic.


Attachment 34509


If you don't believe, then you can send Tom the sum of $186,000,000 in small bills, and he will come to your house and show you himself that it is indeed magic.

Quote:

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Originally Posted by James48843

Forget math explanation.

It's magic.

the Autotracker does it all by magic.

If you don't believe, then you can send Tom the sum of $186,000,000 in small bills, and he will come to your house and show you himself that it is indeed magic.

---

It may not be magic, but one of our old members, "ocean" wrote the massive AutoTracker program for us over the course of a year or so - for free, as a "thanks" to TSP Talk, then basically disappeared. I don't know if I believe in angels, but that was weird to me.

Thank you ocean, wherever you are.

This post is related to this thread in the sense there is a discrepancy between the one-year delta in the TSP C Fund share price and the corresponding delta in the S&P 500 index. Apologize if this isn't the right place to put this but I was just checking my account balance over the past year to compare the share prices of the TSP C Fund to the S&P 500 and there seems to be a large difference between the two deltas when they are compared. I was hoping one of you might be able to help explain the large difference (delta) to me. The delta in share prices for the TSP C Fund from 25 Aug 2014 ($26.1660) to 25 Aug 2015 ($24.9844) is a change of -4.5157%, whereas the delta in the S&P 500 from 25 Aug 2014 (1997.92) to 25 Aug 2015 (1,867.61) is a change of -6.522%, which makes the difference between the share price delta (-4.5157%) and the S&P 500 delta (-6.522%) at 2.00%. I know the share prices of the TSP C Fund do not exactly match the S&P 500 but this 2.00% difference seems to be excessive. Could you please explain this? Here are the numbers:

TSP C Fund as of 25 Aug 2014 = $26.1660 per share
TSP C Fund as of 25 Aug 2015 = $24.9844 per share
Delta = -4.5157% per share

S&P 500 as of 25 Aug 2014 = 1997.92
S&P 500 as of 25 Aug 2015 = 1867.61
Delta = -6.522%

Difference between two indices = 2.00%

What this means in practical terms is that over the same time period the TSP C Fund has lost only 4.5% per share whereas the S&P 500 has lost 6.5% overall. Why?