What was bought, and when
Put a hypothetical $10,000 into SMCI common stock and $10,000 into its 0% convertible senior note due June 15, 2030, using observed prices on June 26, 2025. Mark both on October 2, 2026. Then repeat the exercise from December 31, 2025.
The June entry finishes at $9,437 in the bond and $8,867 in the stock. Both lost money; the bond retained $569 more. Move the entry to year-end and the order reverses: $12,397 in the bond, $14,927 in the stock. The stock leads by $2,530.
These are marked price returns, not returns from an actual portfolio. The visual comparison and a diagram of the convertible appear below.
The issue: zero coupon, with a conversion feature
Supermicro closed this $2.3 billion financing on June 26, 2025. The notes carry no regular coupon. They initially convert at 18.1154 shares per $1,000 principal, equivalent to about $55.20 per share. The company can settle a conversion in cash, shares or a combination. Conversion before December 17, 2029 is conditional; it is not an unrestricted invitation to exchange the bond today. Issue announcement · Terms in the 8-K
This is a hybrid security. Its creditor claim sits ahead of common equity, but its conversion option also links its value to the stock. No coupon does not mean no risk, and senior unsecured does not mean secured by assets.
The first comparison uses a secondary-market print of 111.6422 per $100 principal, not an assumed purchase at par. That distinction matters: using 100 would turn the bond's observed loss into an apparent gain. The original offering was a private placement to qualified institutional buyers; an issue-price allocation was not available to every reader.
Both legs marked on the same date
| Observation | 2030 convertible, per $100 principal | SMCI common share |
|---|---|---|
| June 26, 2025 entry | 111.6422 at 4:03:57 p.m. ET | $49.27 close |
| December 31, 2025 entry | 84.9837 at 9:49:04 a.m. ET | $29.27 close |
| October 2, 2026 mark | 105.3543 at 1:52:24 p.m. ET | $43.69 close |
The bond observations are reported FINRA TRACE transactions, not executable quotes or official closing prices. Each selected print was reported at $1 million-plus par. The June print is close to the equity close; the year-end and October prints are earlier in the day. The dates match; the times do not. Intraday moves and bid/ask differences can affect the comparison. FINRA historical restricted line · Current line · Stock history
The result: the entry date changes the winner
| $10,000 invested from | Bond value | Bond price return | Stock value | Stock price return |
|---|---|---|---|---|
| June 26, 2025 | $9,437 | −5.63% | $8,867 | −11.33% |
| December 31, 2025 | $12,397 | +23.97% | $14,927 | +49.27% |
The bond's first-period lead is loss avoidance, not an income success story. In the year-end comparison, the stock's lower starting price produces the stronger rebound. That is arithmetic, not evidence that one security always wins.
Where the return came from
For each leg, ending value equals $10,000 × ending price ÷ entry price. We allow fractional shares and fractional bond principal to keep the starting dollars equal, although the notes' contractual denomination is $1,000 principal and multiples of it. These are normalized comparisons, not exact purchasable lots.
There is no scheduled coupon income on this note. SMCI common stock pays no regular dividend. The table therefore isolates price performance. Contingent special or additional interest, if any, is excluded; fees, spreads, taxes and reinvestment are also excluded. It should not be read as a fully audited cash-flow total-return record.
The historical bond prints use restricted CUSIP 86800UAE4 / TRACE SMCI6107195; the October mark uses unrestricted CUSIP 86800UAF1 / TRACE SMCI6442482, for the same 0% June 2030 issue. FINRA's original line ends in June 2026. The indenture provides for removing transfer restrictions and changing to an unrestricted identifier. This joins the issue's trading records; changes in trading eligibility and liquidity are another limitation. Original FINRA profile · Current FINRA profile · Indenture, sections 2.10–2.12
Rates, the business, or the equity option?
The observed prices cannot separate those contributions. A conventional bond spread calculation would leave out the conversion option, whose value responds to SMCI's price, volatility and remaining time as well as credit conditions and interest rates.
At the $43.69 stock close, 18.1154 shares were worth approximately $791 per $1,000 principal. The selected bond mark was about $1,054. Those differently timed observations illustrate why today's share-equivalent value is not the bond's entire value: the note also contains a debt claim and years of remaining optionality. They do not establish an arbitrage, a guaranteed price floor or a right to convert immediately.
Buying at 105.3543 and ultimately receiving only 100 at maturity would mean a roughly 5.08% capital loss, before costs, if there were no conversion benefit or other payments. Principal repayment itself remains subject to the issuer's ability to pay. A bond trading above par is not automatically an attractive income investment.
What the filings add
At June 30, 2026, Supermicro reported approximately $7.5 billion in cash against $8.7 billion in bank debt and convertible notes. Full-year sales reached $39.1 billion, while full-year gross margin was 10.8%. Growth and the ability to finance that growth are separate questions. The earnings release also flagged an independent review connected with export-control issues and the possibility that its outcome could affect results and forecasts. Those disclosures belong beside the AI-growth story. Company results
The fiscal 2026 10-K still lists the 2030 notes at $2.3 billion principal, with an 18.1154 conversion rate. The notes are unsecured, and secured creditors have a prior claim to their collateral. The company also has a conditional redemption right beginning in June 2028. These details matter more to this comparison than treating “bond” as shorthand for safety. FY2026 10-K, debt note
What this does and does not say
For the June 2025 buyer, this convertible preserved more marked capital than the stock. For the year-end buyer, the stock captured more upside. Neither result predicts the next period, measures the maximum drawdown along the way, or establishes a risk-adjusted winner.
The useful question is what exposure the buyer wanted: a senior unsecured claim with conditional equity participation, or the full upside and downside of common ownership. The calendar then decides which historical story the numbers tell.
Published October 2, 2026. Prices checked after the equity close; selected bond print is intraday. USD throughout. Educational commentary, not investment advice.
