Wealthy PotBND vs FXNAX: The Same Bond Market in Two Wrappers
Table of Contents
The Short Answer
- Same market, two wrappers. BND is Vanguard's ETF on the Bloomberg U.S. Aggregate Float Adjusted Index. FXNAX is Fidelity's mutual fund on the Bloomberg U.S. Aggregate Bond Index. The two indexes differ only in how they weight bonds the Federal Reserve owns.
- Overlap is 71.8% by our checker, which matches US Treasuries bond by bond and other bonds by issuer. 84.8% of BND's weight sits in holdings FXNAX shares, and 97.8% of FXNAX's in holdings BND shares.
- Fees are a rounding error apart. FXNAX charges 0.025% and BND 0.03%, a gap of 50 cents a year per $10,000.
- The portfolios look alike. On 31 August 2026 BND's average duration was 5.7 years and FXNAX's 5.76 years. On 1 October 2026 BND's 30-day SEC yield was 5.07% and FXNAX's 5.00%.
- Returns track closely. Over the ten years to 30 September 2026, BND returned 1.13% a year at NAV and FXNAX 1.09%. In 2022 they lost 13.15% and 13.04%.
- Decide by account. FXNAX suits a Fidelity account, where its prospectus states there is no purchase minimum. BND suits any brokerage account and trades intraday.
- Do not hold both. It duplicates one position.
Overlap: 71.8% in Our Checker
Our Portfolio Overlap Checker puts BND and FXNAX at 71.8% overlap, across 981 shared holdings. It adds up, for every holding both funds own, the smaller of its two weights. It matches US Treasuries by the exact bond, and corporate bonds and agency mortgage pools by issuer. The data is each fund's SEC Form N-PORT: BND (Vanguard Total Bond Market Index Fund) for 30 June 2026 and FXNAX for 31 May 2026.
US Treasury debt made up 48.1% of BND and 45.4% of FXNAX in those filings, but only the Treasury issues both funds hold count toward the overlap. The largest shared positions are agency mortgage pools, followed by the big corporate issuers, such as JPMorgan Chase, Bank of America and Morgan Stanley, each at around half a percent in both funds.
We also matched the two filings bond by bond, using every security's CUSIP. On that stricter test the overlap is 41.9%, across 4,040 shared securities. The gap from 71.8% comes from the corporate bonds and agency mortgage pools, which the checker matches by issuer: both funds hold only a sample of their index, and mortgage-backed securities come in thousands of separate pools, so the two managers end up with different specific bonds from the same issuers. For how a bond fund will behave, the checker's 71.8% is the more useful number; the 41.9% shows the funds are not carbon copies.
BND vs FXNAX, Side by Side
| BND | FXNAX | |
|---|---|---|
| Full name | Vanguard Total Bond Market ETF | Fidelity U.S. Bond Index Fund |
| Wrapper | ETF share class of Vanguard Total Bond Market Index Fund | Mutual fund |
| Index | Bloomberg U.S. Aggregate Float Adjusted Index | Bloomberg U.S. Aggregate Bond Index |
| Expense ratio | 0.03% | 0.025% |
| Prospectus cost example, $10,000 over 10 years | $39 | $32 |
| Minimum | None beyond what your broker imposes | "There is no purchase minimum for fund shares" |
| Holdings (31 Aug 2026) | 11,421 bonds | 10,602 holdings, 809 issuers |
| Duration (31 Aug 2026) | 5.7 years average duration | 5.76 years |
| 30-day SEC yield, 1 Oct 2026 | 5.07% | 5.00% |
| Portfolio turnover, latest fiscal year | 38% | 45% |
| Net assets | $398.9 billion whole fund, all share classes (31 Aug 2026) | $67.6 billion (30 Sep 2026) |
| Price, 2 Oct 2026 | $69.91 NAV | $9.98 NAV |
| Inception | 3 April 2007 | Fund 8 March 1990; this share class 4 May 2011 |
Two Versions of the Same Index
FXNAX's prospectus says it "seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Bloomberg U.S. Aggregate Bond Index," which it describes as "a broad based, flagship benchmark that measures the investment grade, US dollar-denominated, fixed-rate taxable bond market." BND's prospectus names the Bloomberg U.S. Aggregate Float Adjusted Index.
The difference is narrow. Bloomberg's index methodology (edition dated 15 October 2024) says Federal Reserve purchases and sales of Treasuries are already adjusted for in the flagship US Aggregate. The float-adjusted version "adjusts for US Federal Reserve holdings of US MBS pass-throughs, US agency bonds, and US CMBS bonds, in addition to Treasuries." It changes how much weight those bonds get, not which bonds are in the index. We go through this in detail in AGG vs BND, where AGG tracks the same flagship index as FXNAX.
Both funds sample their index rather than buying every bond. FXNAX's prospectus adds two tools BND's does not list in its summary: derivatives "such as swaps (interest rate, total return, and credit default), options, and futures contracts," along with forward-settling securities, used "to adjust the fund's risk exposure," and investment in "Fidelity's Central funds." These are management tools, not a different strategy, but they are the reason the prospectus lists "Leverage Risk" among FXNAX's principal risks.
Returns Over Identical Periods
| Average annual total return to 30 Sep 2026 | 1 year | 3 years | 5 years | 10 years |
|---|---|---|---|---|
| BND (NAV) | -1.82% | 4.04% | -0.64% | 1.13% |
| FXNAX | -1.85% | 4.00% | -0.67% | 1.09% |
| Calendar year | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|
| BND (NAV) | 2.57% | 3.62% | -0.04% | 8.71% | 7.71% | -1.66% | -13.15% | 5.70% | 1.34% |
| FXNAX | 2.51% | 3.49% | 0.03% | 8.48% | 7.80% | -1.79% | -13.04% | 5.55% | 1.34% |
Over ten years BND is ahead by 0.04 points a year, even though FXNAX charges 0.005 points less. In individual years the lead swaps back and forth by up to about a quarter of a point. 2022 is the reminder that both are bond funds: each lost about 13% that year, and in the three months to 30 September 2026 BND lost 3.43% at NAV. We do not have a verified cause for the year-to-year differences, and sampling plus the index difference make them unsurprising.
Past performance does not guarantee future results. This is educational information, not personalised investment advice.
ETF vs Mutual Fund: How You Buy and Hold
This is where the two funds genuinely differ.
- Pricing. FXNAX trades once a day: "The price to buy one share is its net asset value per share (NAV). Shares will be bought at the NAV next calculated after an order is received in proper form." BND trades all day at a market price that, in Vanguard's words, "may be more (premium) or less (discount) than the NAV of the shares."
- Where you can buy. FXNAX's prospectus lists "a Fidelity® brokerage or mutual fund account," a retirement account, or "an investment professional." BND can sit in any brokerage account. We did not verify whether or at what cost other brokers offer FXNAX, so check before assuming you can buy or transfer it elsewhere.
- Minimums and automation. FXNAX's prospectus states "There is no purchase minimum for fund shares," and a mutual fund buys exact dollar amounts. BND's prospectus says there is no minimum "unless imposed by your brokerage firm." Fractional ETF shares and automatic ETF purchases depend on your broker.
- Dividends. Vanguard's statutory prospectus says income dividends on its ETF shares are "declared and distributed monthly." We did not confirm FXNAX's schedule from a filing, so check Fidelity's fund page if timing matters to you.
For the general case of mutual fund versus ETF share classes, see ETF vs index fund, and for Vanguard's own mutual fund version of BND, see BND vs VBTLX.
Tax: What the Filings Show
ETFs are often described as more tax-efficient than mutual funds. For these two bond funds the SEC-mandated after-tax returns in each prospectus show no meaningful difference over the same period:
| Periods ended 31 Dec 2024 | 1 year | 5 years | 10 years |
|---|---|---|---|
| BND, before taxes (NAV) | 1.34% | -0.29% | 1.34% |
| FXNAX, before taxes | 1.34% | -0.31% | 1.33% |
| BND, after taxes on distributions | -0.15% | -1.39% | 0.23% |
| FXNAX, after taxes on distributions | -0.04% | -1.39% | 0.22% |
| BND, after taxes on distributions and sale | 0.79% | -0.66% | 0.55% |
| FXNAX, after taxes on distributions and sale | 0.79% | -0.65% | 0.55% |
Most of what a bond fund pays out is interest, which is taxed as ordinary income whichever wrapper delivers it. FXNAX's prospectus says its distributions "generally will be taxed as ordinary income or capital gains, and may also be subject to state or local taxes." The part of either fund's income that comes from Treasuries may be exempt from state tax depending on your state, but both hold roughly the same share of Treasuries, so this does not separate them.
Which One Fits Your Account?
- Your money is at Fidelity: FXNAX. It is Fidelity's own fund, costs 0.025%, has no purchase minimum, and buys exact dollar amounts.
- Your money is at Vanguard, Schwab or another broker: BND. It trades anywhere at 0.03%.
- Your 401(k) offers one of them: use the one on the menu. The difference between them is far smaller than the difference between holding bonds and not.
- You might move brokers later: BND is the more portable choice, since ETF shares can be held at any brokerage. Check before assuming a mutual fund will transfer in kind.
- You want to invest a fixed dollar amount every month: a mutual fund like FXNAX buys exact dollar amounts at NAV, which keeps this simple. With BND it depends on your broker's fractional-share and recurring-investment features.
- You already hold one in a taxable account: switching would mean selling, with whatever gain or loss that realises, for a fee difference of half a basis point. Not worth it on cost grounds.
- You want short-term cash instead: neither. See BND vs SGOV.
Sources & Methodology
Every figure on this page was read from the primary source named below. Each fee comes from that fund's own summary prospectus. Portfolio statistics and recent returns come from Vanguard's and Fidelity's own fund pages, with the issuer's as-of date. The overlap comes from SEC Form N-PORT filings. No figure came from a data aggregator or another comparison site.
- Vanguard Total Bond Market ETF (BND), Summary Prospectus dated 28 April 2026 (Form 497K, SEC EDGAR): the 0.03% fee, cost example, index, 38% turnover, no-minimum and premium/discount language, and calendar-year returns.
- Vanguard Bond Index Funds statutory prospectus dated 28 April 2026 (Form 485BPOS, SEC EDGAR): the monthly dividend schedule for ETF shares.
- BND Summary Prospectus dated 29 April 2025 (Form 497K, SEC EDGAR): before- and after-tax returns for periods ended 31 December 2024.
- Fidelity U.S. Bond Index Fund (FXNAX), Summary Prospectus dated 30 October 2025 (Form 497K, Fidelity Salem Street Trust, SEC EDGAR): the 0.025% fee, cost example, index and strategy, derivatives and Central funds language, 45% turnover, no purchase minimum, NAV pricing, tax sentence, and before- and after-tax returns.
- Vanguard BND profile and Fidelity FXNAX research page: yields, duration, holdings counts, net assets, NAV and returns to 30 September 2026.
- Bloomberg Fixed Income Index Methodology, 15 October 2024: the float adjustment rules.
- SEC Form N-PORT: Vanguard Total Bond Market Index Fund for 30 June 2026 and Fidelity U.S. Bond Index Fund for 31 May 2026.
How the overlap was computed. For each holding both funds held, we took the smaller of its two weights and added them up, using the same N-PORT data and method as the Portfolio Overlap Checker, which matches US Treasuries by exact bond and other bonds by issuer. The bond-by-bond figure uses the same filings with every bond matched by CUSIP. The two filings are a month apart.
What we could not verify: whether other brokers sell FXNAX or charge to buy it, whether it transfers in kind away from Fidelity, and FXNAX's distribution schedule from a filing. When FXNAX's next annual prospectus is filed, the calendar-year table should gain 2025 for both funds.
This article is for general education only and is not investment, tax or legal advice. Bond funds can and do lose money; both of these lost about 13% in 2022. Yields, prices and portfolio statistics change daily. All figures were checked on 5 October 2026. Confirm current figures with Vanguard and Fidelity before acting, and consider a licensed professional for advice on your situation.
FAQ: BND vs FXNAX
Is FXNAX the same as BND?
Nearly, but not exactly. They track two versions of the Bloomberg US Aggregate index that differ only in how bonds held by the Federal Reserve are weighted. Our checker puts their overlap at 71.8%. Their durations were 5.7 and 5.76 years on 31 August 2026.
Which is cheaper, BND or FXNAX?
FXNAX, at 0.025% against BND's 0.03%. On $10,000 that is $2.50 against $3 a year.
Which has performed better?
Over the ten years to 30 September 2026, BND returned 1.13% a year at NAV and FXNAX 1.09%. In single years the lead switches. In 2022 BND lost 13.15% and FXNAX 13.04%.
Can I buy FXNAX outside Fidelity?
Its prospectus lists a Fidelity brokerage or mutual fund account, a retirement account, or an investment professional. Some other brokers may offer it, possibly with a fee. We did not verify any, so check with yours. BND is available at any brokerage.
Is BND more tax-efficient than FXNAX because it is an ETF?
Not in a way the filings show. Over the ten years to 31 December 2024, after taxes on distributions and sale, both returned 0.55% a year. Most of a bond fund's payout is interest, taxed as ordinary income either way.
Should I hold both BND and FXNAX?
No. With 71.8% overlap, and both funds sampling the same bond market, they are the same position. Pick the one that suits your account.
What is a better short-term alternative to either?
For money you need within a year or two, a Treasury bill fund or money market fund. See BND vs SGOV.
Cite This Page
Journalists, educators and bloggers are welcome to cite this comparison. Please link back so readers can reach the filings themselves.
"BND vs FXNAX: The Same Bond Market in Two Wrappers." Wealthy Pot, 2026. https://wealthypot.com/bnd-vs-fxnax/
Related comparisons: AGG vs BND · BND vs VBTLX · FXAIX vs VOO · ETF vs index fund · All ETF comparisons
