Guide

Commercial paper explained

Harbor Capital’s treasury team parked $42 million in a prime money market fund and assumed the holdings were “all government.” A month-end fact sheet showed 38% in commercial paper (CP) from three industrial issuers they had never heard of. When one issuer was downgraded from A1/P1 to A2/P2, the fund gated redemptions for two days while it sold paper into a thin market. The treasurer had confused fund label with underlying credit. CP is the plumbing of corporate cash management: unsecured, short-maturity promissory notes that blue-chip firms issue to fund payroll, inventory, and working capital without drawing bank credit lines. It also sits inside repo collateral chains and prime MMF portfolios. This guide covers issuance mechanics, discount yield math, rating tiers, dealer vs direct programs, asset-backed CP, the Harbor Capital sleeve refactor, a technique decision table vs T-bills and bank lines, pitfalls, and a production checklist.

What commercial paper is

Commercial paper is an unsecured promissory note issued by a corporation (or finance subsidiary) to raise cash for a short period, typically overnight to 270 days. U.S. securities law treats paper with maturities beyond 270 days as registered debt, so issuers stay inside that window to avoid SEC registration. There is no coupon payment schedule on most CP: investors buy at a discount to face value and receive par at maturity, though interest-bearing (zero-discount) programs exist for certain tax jurisdictions.

CP is not a bank loan and not a bond. It is sold in the wholesale money market to institutional buyers — money market funds, corporate treasuries, asset managers, and bank trading desks. Issuance is repetitive: a company with a $5 billion CP program may roll $200–800 million outstanding daily, maturing old notes and issuing new ones at prevailing rates. Liquidity depends entirely on investor appetite and the issuer’s credit rating; there is no exchange, no retail ticker, and often no secondary market beyond dealer inventory.

Issuance mechanics: programs, dealers, and settlement

CP programs and backup lines

Large issuers register a CP program with a paying agent and one or more dealer banks (JPMorgan, Citi, BofA, etc.). The program documents cap outstanding volume and define eligible maturities. Rating agencies assign short-term ratings (S&P A-1+, A-1, A-2; Moody’s P-1, P-2; Fitch F1+, F1). Only top-tier names reliably place paper at tight spreads; A2/P2 issuers may issue only in stress or at wide concessions.

Investors demand a backup liquidity facility — a committed bank line that draws if the CP market closes. Without it, a maturity wall during a credit scare can force fire sales of long-term assets. Backup fees are a hidden cost of CP funding; treasurers compare all-in CP yield plus line fees to term loans and revolvers.

Discount yield vs bond yield

CP quotes as a discount rate on face value, not a bond-equivalent yield. A 90-day note at 5.00% discount on $1,000,000 face costs roughly $987,500 upfront; the investor earns $12,500 over 90 days. Converting discount to bond-equivalent yield (BEY) matters when comparing CP to T-bills or SOFR-linked repo. Day-count conventions (ACT/360 vs ACT/365) also shift comparisons by a few basis points — material at scale.

Settlement and DTC

Most U.S. CP clears through DTC in T+0 or T+1 cycles. Dealers warehouse inventory between issuance and fund allocation. During the 2008 financial crisis and March 2020 COVID shock, dealer balance-sheet constraints and redemption waves in prime MMFs froze CP rolls for lower-rated names, illustrating why credit spread widening in CP often precedes wider corporate bond spreads.

Issuer types and asset-backed commercial paper

Financial vs industrial issuers

Financial CP comes from banks, finance companies, and broker-dealers funding receivables and trading books. Industrial CP funds working capital at manufacturers, tech firms, and retailers with strong balance sheets. Spread hierarchy generally runs: sovereign < financial A1 < industrial A1 < A2 tier. Seasonal issuers (retail before holidays) show predictable supply bumps that MMF portfolio managers anticipate.

ABCP conduits

Asset-backed commercial paper (ABCP) is issued by bankruptcy-remote conduits that hold trade receivables, credit-card receivables, or other ABS collateral. Investors rely on pool credit enhancement and liquidity puts from sponsoring banks, not the sponsor’s standalone rating alone. ABCP blew up in 2007–2008 when conduit assets (mortgage-backed securities) were marked down and banks refused to honor liquidity puts. Post-crisis reform shrank ABCP outstanding, but it still funds securitization pipelines. Treat ABCP as structured credit, not generic corporate IOUs.

Who buys CP and why it matters for cash investors

Prime money market funds are the largest CP buyers. Government-only MMFs hold Treasuries and repo exclusively; prime funds hunt extra yield in A1/P1 CP and CDs. Corporate treasurers also buy peer CP in direct-placement programs when they trust counterparty credit. Central banks and sovereign wealth funds participate selectively.

For a retail investor holding cash in a brokerage sweep, CP exposure is indirect but real: read the fund’s schedule of investments and weighted average life. A 45-day WAL with 30% CP from single-sector names concentrates rollover risk. During stress, the fund may impose gates or liquidity fees (allowed under SEC reforms) while selling CP at haircuts.

Harbor Capital cash sleeve refactor (worked example)

Problem: Harbor parked operating cash in a prime MMF for yield, but quarterly board risk limits capped single-name corporate exposure at 2% of NAV. The fund held five CP names above 3% each; downgrade of one A1 issuer would breach policy.

Changes:

Split cash: 70% to a government MMF (zero CP), 30% to a separately managed ladder of direct-purchased T-bills via the custodian.
For the remaining yield sleeve, negotiated a direct CP program with two A1+ industrial issuers Harbor already had long-term banking relationships with — bilateral limits instead of fund concentration.
Mandated maximum 60-day WAL on any CP holding; no A2/P2 paper.
Added weekly CP spread monitor vs 3-month T-bill and SOFR OIS; alert if any name widens more than 15 bp vs sector median.
Documented backup-line status for each direct CP counterparty in the risk register.

Result: Seven-day yield fell 28 bp versus the old prime fund, but single-name CP risk dropped to zero in pooled vehicles and board limits were met. The treasurer accepted lower yield for definable credit transparency — the correct trade for operating cash, not return-seeking capital.

Technique decision table

When CP fits	Prefer something else
Issuer with A1/P1 rating needs flexible daily funding under $1B	Below investment grade — term loan or secured revolver
Investor seeking 10–40 bp over T-bills with 30–90 day horizon	Cannot tolerate credit events — government MMF or T-bills only
ABCP conduit with strong liquidity puts and diversified receivables	Opaque pool collateral — pass or demand sponsor guarantee
Treasurer with issuer relationships doing direct-placement CP	Retail cash — FDIC HYSA or government MMF
Secured overnight funding via dealer repo on CP inventory	Long-duration corporate bond exposure — not CP’s purpose

Common pitfalls

Confusing fund label with holdings — “Cash fund” or “prime” does not mean government-only; read the fact sheet.
Discount vs BEY mismatch — comparing CP discount rate to bond yield overstates CP attractiveness at short maturities.
Ignoring backup line expiry — CP programs without renewed bank commitments cannot roll during market stress.
Concentration in one sector — auto, energy, or tech CP clusters correlate in downturns.
Assuming T+0 liquidity — funds may gate; CP may not trade except at dealer bid.
ABCP treated as corporate CP — conduit structure and liquidity puts require separate diligence.
Year-end window dressing — issuers flood CP in December; spreads can compress artificially then snap wider in January.
Rating agency lag — A1 issuers can be downgraded without warning; monitor spreads, not just letters.
Tax reporting surprises — OID on discount paper flows to 1099-INT; state tax treatment varies for MMF dividends.

Production checklist

Confirm issuer short-term rating (A1/P1 or better) and outlook.
Verify backup liquidity facility size, expiry, and drawing conditions.
Convert quoted discount rate to bond-equivalent yield before benchmarking.
Match day-count convention (ACT/360) in yield calculators.
Cap single-issuer CP exposure as percent of portfolio NAV.
Set maximum WAL and maturity bucket limits for MMF holdings.
Read fund schedule of investments monthly; track CP sector weights.
Stress-test: what happens if one A1 name is downgraded to A2 overnight?
For ABCP, review conduit assets, enhancement, and sponsor liquidity puts.
Document alternative funding (revolver draw) if CP market closes.
Monitor CP-OIS or CP-T-bill spread time series for early warning.
Align cash segmentation: operating (safety) vs strategic (yield).

Key takeaways

Commercial paper is unsecured, short-term corporate funding rolled daily in the wholesale market — not a bank deposit or government guarantee.
Harbor Capital cut hidden CP concentration by splitting government MMF, T-bill ladder, and bilateral direct CP with relationship banks.
Prime money market funds are CP buyers; read the fact sheet before assuming your cash is risk-free.
Discount yield math and day-count conventions matter when comparing CP to T-bills and repo.
ABCP is structured credit with conduit risk — diligence beyond a single corporate rating.