What is the deal with the I Fund?

[SkyPilot]

That's what I thought. But the same happens for S & C. I need a course in finance or something.

This publication is a basic place to start.

https://www.tsp.gov/PDF/formspubs/tspbk08.pdf

"Currency risk — The risk that the
value of a currency will rise or fall relative
to the value of other currencies.
Currency risk occurs with investments
in the I Fund because of fluctuations in
the value of the U.S. dollar in relation
to the currencies of the 21 countries in
the EAFE index."