Buying a share involves a visible commission and a bid-ask spread that anyone can see on screen. Buying a bond often involves no commission at all, which sounds like an improvement and usually is not.
Most bond trades are principal transactions. The dealer sells from inventory at a price that already includes their compensation, so the cost is embedded in the price rather than listed separately. Nothing on the confirmation says “fee” because, technically, there wasn’t one.
That structure explains why two investors buying the same bond on the same day can pay materially different amounts, and why the difference correlates with how much they bought.
Why the Structure Differs From Equities
Anyone working out how to buy bonds meets a market organised on entirely different lines from the equity market they already know.
The differences that drive cost:
- No central order book for most issues, so there is no single displayed price;
- Dealer intermediation, where the counterparty is a firm selling from inventory;
- Enormous issue counts, with a single company often having dozens of outstanding bonds;
- Thin trading in any individual issue, many of which do not trade on a given day.
The third and fourth points compound. Equity liquidity concentrates in one line per company, while bond liquidity fragments across every issue that company has ever sold.
What the Cost Data Shows
Regulators publish comparative transaction cost figures, and the differences by sector are consistent.
Analysis from the municipal market regulator found transaction costs higher for municipal securities at 38 basis points than for corporate bonds at 25 basis points, and slightly higher compared to agency securities.
The same body has separately examined why municipal transaction costs rose after 2022, attributing part of the increase to market volatility during a period of rising rates and inflation.
Those figures are averages across all trade sizes. The retail experience sits above them, because cost in this market scales inversely with size.
The Disclosure Rule and Its Effect
Until recently the embedded cost was genuinely invisible. That changed in 2018.
Research on the change describes the sequence: the self-regulator adopted a rule requiring broker-dealers to disclose their markups when they buy corporate bonds and sell them to retail investors the same day, applying from May 2018. Examining the result, the researchers found that the markup on same-day retail trades declined by about 5% compared to trades not subject to the disclosure, or from about $431 to $409 on a $50,000 trade.
Two things stand out. Brokerage firms resisted this disclosure for roughly two decades. And simply requiring the number to be printed reduced it.
The same research notes that sophisticated investors could already estimate markups from the public trade reporting database, but that doing so imposed processing costs, creating an information gap between retail investors and market professionals.
What the Rule Covers
The scope is narrower than it first appears. The requirement applies to same-day principal transactions where the dealer has an offsetting trade of equal or greater size.
A trade held in inventory overnight falls outside it. So does a trade below the offsetting threshold. The disclosure is real and it does not cover everything.
Why Size Matters So Much
The pattern across this market is that small trades cost more per dollar, and the gap is not marginal.
Research has also shown that bid-ask spreads tend to be higher for smaller bond investors than for larger market participants, which can make small trades more expensive as a percentage of the amount invested.
For an individual investor the practical consequence is that buying a single bond in small size is among the most expensive ways to obtain fixed-income exposure, measured as a percentage of the amount invested.
How to Check Before Trading
Public reporting makes verification possible for anyone willing to look:
- Look up recent trades in the specific issue using its identifier on the public reporting system;
- Compare the offered price against what institutions paid in recent transactions;
- Check the trade sizes alongside the prices, since large and small trades price differently;
- Read the markup figure on the confirmation where the disclosure rule applies;
- Ask for the markup on trades where disclosure is not required, since brokers may disclose voluntarily.
The first step takes a few minutes and is the closest thing this market offers to a price check.
What Reduces the Cost
Several choices move the figure meaningfully:
- Trading in larger size, which improves pricing per dollar;
- Choosing more actively traded issues over obscure ones;
- Using funds for small allocations, where the fund trades at institutional scale;
- Holding to maturity, which avoids paying the spread a second time;
- Comparing two dealers on the same issue where possible.
The third point is the one that resolves the problem for most individual investors rather than mitigating it. The cost of trading small in this market is structural, and pooling is the mechanism that removes it.
