TSPF vs VBTLX: 94% overlap
TSP F Fund — shown via aggregate-bond proxy and Vanguard Total Bond Market Index Admiral share 93.9% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
You would hold two tickers and get the diversification of 1.1. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
TSPF and VBTLX hold 1,682 of the same securities. The ten contributing most to the overlap figure:
| Holding | in TSPF | in VBTLX | Δ |
|---|---|---|---|
| UST-3-10Y | 21.0% | 21.3% | 0.2% |
| AGENCY-MBS | 24.1% | 20.3% | 3.7% |
| UST-0-3Y | 16.1% | 16.7% | 0.6% |
| UST-10Y+ | 9.3% | 10.2% | 0.9% |
| CASH | 2.7% | 1.1% | 1.6% |
| 46647P | 0.5% | 0.6% | 0.0% |
| 06051G | 0.5% | 0.5% | 0.0% |
| 68389X | 0.3% | 0.3% | 0.0% |
| 38141G | 0.3% | 0.3% | 0.0% |
| 459058 | 0.3% | 0.4% | 0.1% |
Where TSPF and VBTLX differ
Sector weights as a share of each fund, ordered by the size of the gap rather than the size of the sector — two funds that overlap heavily still usually diverge somewhere.
| Sector | TSPF | VBTLX | Δ |
|---|---|---|---|
| MBS Pass-Through | 24.1% | 20.3% | +3.7pp |
| Cash & Other | -2.1% | 0.0% | −2.1pp |
| Treasuries | 46.5% | 48.2% | −1.7pp |
| Cash and/or Derivatives | 2.7% | 1.1% | +1.6pp |
| Unclassified | 0.0% | 0.7% | −0.7pp |
| Supranational | 0.9% | 1.4% | −0.5pp |
| Corporate — industrial & other | 14.3% | 14.6% | −0.4pp |
| CMBS | 0.7% | 0.4% | +0.3pp |
Δ is TSPF minus VBTLX, in percentage points. Sector data is not published by every issuer, so “Unclassified” is a real category rather than a gap in the table.
What each fund holds alone
0.4% of TSPF by weight, held in no part of VBTLX.
0.7% of VBTLX by weight, held in no part of TSPF.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| TSPF | VBTLX | |
|---|---|---|
| Top 10 holdings | 75.3% | 71.7% |
| Positions held | 1,864 | 2,047 |
| Cost per $10,000 held, per year | $5 | $4 |
Cost is the expense ratio applied to $10,000; it excludes any brokerage commission, bid-ask spread or tax consequence. Figures are facts about the funds, not a suggestion about which to hold.
Frequently asked
How much do TSPF and VBTLX overlap?
TSPF and VBTLX overlap 93.9% by portfolio weight — they are effectively the same fund. They share 1,682 holdings. The figure comes from current issuer holdings files (TSPF as of 2026-07-23, VBTLX as of 2026-06-30).
How is the overlap between TSPF and VBTLX calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If TSPF holds a stock at 6% and VBTLX holds the same stock at 4%, 4% counts as shared. The result is bounded between 0% and 100%, and it is computed after looking through any fund-of-funds to the underlying holdings.
Is it redundant to hold both TSPF and VBTLX?
That depends on your goals — we state facts, not advice. At 93.9% overlap, most of what one fund holds, the other holds too. Expense ratios: TSPF 0.05% versus VBTLX 0.04%.
What does TSPF own that VBTLX doesn't?
TSPF holds 1,864 positions and VBTLX holds 2,047; 181 of TSPF's positions don't appear in VBTLX at all, and they are 0.4% of TSPF by weight.
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Sources: issuer holdings files, TSPF as of 2026-07-23, VBTLX as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.