Who is in the I-fund?

[TommyIV]

Almost through Wednesday’s trading session, the I-fund is on track to deliver a modest gain of about 0.1%, while C and S-fund investors are staring at losses of roughly 0.5%. With less than three hours until the close, the message is clear: the I-fund continues to outpace its U.S. counterparts. That has been the theme of 2025, and it’s especially evident this month.

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The I-fund’s Rare Streak​

For most TSP investors, the I-fund is an afterthought, overshadowed by the C and S-funds. The last time it pulled ahead for an entire year was 2022—when it lost less than the others (-13% versus -18% for the C-fund and -26% for the S-fund).

This year, the tables have turned. The I-fund has been a powerhouse, climbing 22% year-to-date while the C and S-funds are stuck below 10%.

The strength hasn’t let up in August. With the C and S-funds fighting to stay positive for the month, the I-fund has already gained 4.3%.

That raises the question: How many TSP Talk AutoTracker members are actually riding the I-fund’s success?

Want to see where top TSP investors are putting their money each day? Start a free trial of the Last Look Report and get real-time insights 30 minutes before the IFT deadline.

100% Single-Fund Holders​

Among active AutoTracker members (those who’ve logged in this year):

• 13 hold 100% in the I-fund
• 35 hold 100% in the C-fund
• 75 hold 100% in the S-fund
• 136 hold 100% in the G-fund
  

Clearly, the I-fund is not the go-to choice for single-fund investors. Despite its underperformance this year, the S-fund remains the preferred aggressive play in the community—including from MRJ, the current 2025 AutoTracker leader, and NtvTxan, ranked #3.

The one exception at the top: nightman (ranked #4), who is fully invested in the I-fund.

Partial Allocations: 50% or More​

Beyond the all-in investors, a small group is giving the I-fund meaningful weight.

• 15 members hold 50% or more in the I-fund
• 97 hold 50% or more in the C-fund
• 76 hold 50% or more in the S-fund

Some overlap exists. For example, BHRUNIKH (ranked #2 overall) is evenly split: 50% C-fund, 50% I-fund.

Totals:

• I-fund: 28 members with ≥50%
• C-fund: 132 members with ≥50%
• S-fund: 151 members with ≥50%

The takeaway is clear: C and S still dominate. But the I-fund has a foothold among a smaller, more selective group.


Among the Top 100

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Last Look Subscribers already know the I-fund shows up more prominently among the leaders.

Among the top 100 performers of 2025 (active members only):

• 16 hold 50% or more in the I-fund
• 23 hold 50% or more in the C-fund
• 26 hold 50% or more in the S-fund

Only one top-100 member has been parked in 100% I-fund all year. The rest have actively rotated, but the data shows the I-fund is no longer ignored at the top.

Average allocation of the top 100:

• G: 26.2%
• F: 1.5%
• C: 24.4%
• S: 26.8%
• I: 16.9%

For comparison, the I-fund average across all active members is just 7.4%.

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Conclusion

The I-fund’s strong 2025 has not translated into broad adoption among AutoTracker members, but it has become a tool used more often by the best-performing investors. That doesn’t guarantee future success—but it does suggest the I-fund deserves more than “afterthought” status in TSP strategies.

Learn more about what you’re actually investing in with the I-fund here.

Stay on top of AutoTracker trends (and support TSP Talk) by subscribing to the Last Look Report.


This is not a recommendation to buy the I-fund. I currently hold no shares of the I-fund or I-fund-related ETFs.

 

[nasa1974]

We have talked on and off for a few years how the "I" fund has been lagging behind the "S" and "C" funds and one day it will take off. I guess it's day has come.

 

[Viettim]

I have always held some in the I-Fund, I have faith it will continue to increase.

 

[James48843]

I’m trying think this through:

Since the I fund reconfigured, are the holdings now more likely to benefit or be harmed by the world changes in US tariffs?

And what is the dollar gong to do? Will it weaken? Or strengthen?

Because those are the force multipliers in using the I fund as a portfolio tool.

When the dollar is strong, do you buy more I? Knowing that weakening will mean better performance?

That’s the kicker right now. How do we score those two?

 

[JTH]

I’m trying think this through:

Since the I fund reconfigured, are the holdings now more likely to benefit or be harmed by the world changes in US tariffs?

And what is the dollar gong to do? Will it weaken? Or strengthen?

Because those are the force multipliers in using the I fund as a portfolio tool.

When the dollar is strong, do you buy more I? Knowing that weakening will mean better performance?

That’s the kicker right now. How do we score those two?

The biggest issue I have with the I-Fund, is it's very difficult to measure the risk.

Some valid points of contention, I Fund has Mexico, Brazil and many other countries targeted with unpredictable tariffs. While we can track 100% of the C-Fund, and I've tracked down about 95% of the S-Fund, I can't get close to tracking the moving parts of the secret I-Fund. Then add about 48% is from developed countries comprised of old over-regulated non-innovative companies.

So we get to place a bet on the direction of the dollar against 20+ currencies, sprinkle in 3,600+ developed and 2,000+ undeveloped companies, and add in the unstable tariff policies, all while forecasting a Global slowdown in growth.

This has been the dollar's largest half-year decline in 50 years, if we think this can continue, then I guess the I-Fund is a good place to be....

 

[weatherweenie]

Back in the day of day/unlimited moves in the TSP, there was a real or perceived possibility of playing the days of an I fund/TSP correction, or adjustment.

 

[Boghie]

Look at 2009.

It BOOMED massively. There were a few old timers who rode that thang to 40%+ gains.

 

[nasa1974]

Back in the day of day/unlimited moves in the TSP, there was a real or perceived possibility of playing the days of an I fund/TSP correction, or adjustment.

Those where the fun days.

Look at 2009.

It BOOMED massively. There were a few old timers who rode that thang to 40%+ gains.

It was that one day "I" fund move that got some of us in trouble and how we lost our daily IFT's.