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.