Eaton Vance Senior Income Trust

N-CSR 1 d100896dncsr.htm EATON VANCE SENIOR INCOME TRUST Eaton Vance Senior Income Trust

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED

MANAGEMENT INVESTMENT COMPANIES

Investment Company Act File Number: 811-09013

Eaton Vance Senior Income Trust

(Exact Name of Registrant as Specified in Charter)

One Post Office Square, Boston, Massachusetts 02109

(Address of Principal Executive Offices)

Deidre E. Walsh

One Post Office Square, Boston, Massachusetts 02109

(Name and Address of Agent for Services)

(617) 482-8260

(Registrant’s Telephone Number)

June 30

Date of Fiscal Year End

June 30, 2026

Date of Reporting Period

Item 1. Reports to Stockholders

(a)

Eaton Vance

Senior Income Trust (EVF)

Annual Report

June 30, 2026

Commodity Futures Trading Commission Registration. The Commodity Futures Trading Commission (“CFTC”) has adopted regulations that subject registered investment companies and advisers to regulation by the CFTC if a fund invests more than a prescribed level of its assets in certain CFTC-regulated instruments (including futures, certain options and swap agreements) or markets itself as providing investment exposure to such instruments. The investment adviser has claimed an exclusion from the definition of “commodity pool operator” under the Commodity Exchange Act with respect to its management of the Fund. Accordingly, neither the Fund nor the adviser with respect to the operation of the Fund is subject to CFTC regulation. Because of its management of other strategies, the Fund's adviser is registered with the CFTC as a commodity pool operator. The adviser is also registered as a commodity trading advisor.

Fund shares are not insured by the FDIC and are not deposits or other obligations of, or guaranteed by, any depository institution. Shares are subject to investment risks, including possible loss of principal invested.

Annual Report June 30, 2026

Eaton Vance

Senior Income Trust

Table of Contents
Management’s Discussion of Fund Performance	2
Performance	4
Fund Profile	5
The Fund's Investment Objectives, Principal Strategies and Principal Risks	6
Endnotes and Additional Disclosures	12
Financial Statements	13
Report of Independent Registered Public Accounting Firm	41
Federal Tax Information	42
Dividend Reinvestment Plan	43
Board of Trustees’ Contract Approval	45
Management and Organization	49
U.S. Customer Privacy Notice	51
Potential Conflicts of Interest	54
Important Notices	62

Table of Contents

Eaton Vance

Senior Income Trust

June 30, 2026

Management’s Discussion of Fund Performance^†

Economic and Market Conditions

The senior floating-rate corporate loan market registered a positive performance for the 12-month period ended June 30, 2026, as the Morningstar® LSTA® US Leveraged Loan Index^SM (the Index) returned 4.36%. High interest income was partially offset by a decline in market value, as late-period weakness related to software concerns weighed on the market.

Key Drivers

• Income-led returns: Elevated base rates drove high coupon income, which accounted for the majority of total returns across the period.

• Shifting sentiment results in bifurcated market: Strong risk appetite in mid-2025 gave way to a more cautious tone in late 2025, followed by volatile swings in the second half of the period.

• Software drives 2026 drawdown: Weakness in January, February, and June 2026 — led by investor concerns over AI’s impact on the software sector — weighed on loan prices and performance.

Credit Quality & Performance

• BB-rated loans outperformed: Single-B loans (62% of the Index) returned 4.37% for the period, while BB-rated loans (23% of the market) returned 5.71%. Loans rated CCC (4.50% of the market) posted an annual return of -3.35%.

• Market bifurcation: The average bid price of the Index fell to $94.96 from $97.07 a year ago. Beneath the surface, the share of loans priced below $90 came to 13% at period end, while 22% of the market was priced at par or higher, a sign of the growing split between stronger and weaker credits.

• Auto components, building products lag: Following the First Brands bankruptcy in September, the auto components segment returned -12.30% for the 12-month period. Building products also struggled due to persistently high mortgage rates and tariffs, returning -3.20%.

Market Technicals

• Repricings and refinancings lead issuance volume: Total institutional loan market activity for the 12-month period was over $425 billion, although repricing and refinancing activity accounted for a majority of issuance.

• Institutional demand remains strong: Collateralized Loan Obligation (CLO) issuance totaled $189 billion over the period, with calendar year 2025 marking the strongest year of CLO formation on record.

• Fund outflows persist: Leveraged loan retail funds saw total net outflows of $11 billion, with sustained redemptions amid volatile markets, software worries and falling interest rates.

Fundamental Factors

• Default rates: At period-end, the trailing 12-month default rate stood at 0.97% by par amount (down from 1.11% a year ago) and 1.34% by issuer count (up from 1.25%). Including liability management exercises, the default rate by issuer count fell to 2.95%, down 151 basis points year-over-year.

• Stress indicators remained low but worsened during the period: Loans trading under $80 climbed to 6.90% of the market, compared with 3.10% at the start of the 12-month period. The end-of-period reading is slightly above long-term distress rate averages.

Fund Performance

For the 12-month period ended June 30, 2026, Eaton Vance Senior Income Trust (the Fund) returned 2.86% at net asset value of its common shares (NAV), underperforming its benchmark, the Morningstar® LSTA® US Leveraged Loan Index^SM (the Index), which returned 4.36%.

See Endnotes and Additional Disclosures in this report.

Past performance is no guarantee of future results. Returns are historical and are calculated net of management fees and other expenses by determining the percentage change in net asset value (NAV) or market price (as applicable) with all distributions reinvested in accordance with the Fund’s Dividend Reinvestment Plan. Furthermore, returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Performance at market price will differ from performance at NAV due to variations in the Fund’s market price versus NAV, which may reflect factors such as fluctuations in supply and demand for Fund shares, changes in Fund distributions, shifting market expectations for the Fund’s future returns and distribution rates, and other considerations affecting the trading prices of closed-end funds. Investment return and principal value will fluctuate so that shares, when sold, may be worth more or less than their original cost. Performance for periods less than or equal to one year is cumulative. Performance is for the stated time period only; due to market volatility, current Fund performance may be lower or higher than the quoted return. For performance as of the most recent month-end, please refer to eatonvance.com.

Table of Contents

Eaton Vance

Senior Income Trust

June 30, 2026

Management’s Discussion of Fund Performance^† — continued

The Fund’s use of investment leverage during the period detracted from relative performance versus the Index, which does not employ leverage. The Fund’s use of leverage has the effect of achieving additional exposure to the loan market, magnifying exposure to the Fund’s underlying investments in both up-and-down market environments. As loan prices generally declined during the period, this hurt relative performance.

Selection was also a detractor from relative performance results during the period. Loan selection within the household durables, chemicals, food products, and professional services industries detracted the most. Selection within the BB-rating tier also dragged on relative results. Elsewhere, a Fund overweight exposure to the automobile components segment detracted from performance relative to the Index.

On the other hand, the Fund’s selection within the same automobile components industry added the most to relative performance during the period, as the Fund had an underweight exposure to a large auto parts supplier included in the Index that unexpectedly filed for bankruptcy at the end of September 2025.

Elsewhere, the Fund’s underweight allocation to the software sector also added to relative performance. An out-of-Index allocation to Collateralized Loan Obligation (CLO) debt contributed to relative results. Additionally, the repurchase of a portion of the Fund’s auction preferred shares at a discount to their par value contributed to performance versus the Index.

See Endnotes and Additional Disclosures in this report.

Table of Contents

Eaton Vance

Senior Income Trust

June 30, 2026

Performance

Portfolio Manager(s) Daniel P. McElaney, CFA and Peter M. Campo, CFA

% Average Annual Total Returns^1,2	Inception Date	One Year	Five Years	Ten Years
Fund at NAV	10/30/1998	2.86%	5.32%	6.25%
Fund at Market Price	—	(4.71)	3.03	6.00

Morningstar® LSTA® US Leveraged Loan Index^SM	—	4.36%	6.01%	5.50%

% Premium/Discount to NAV³
As of period end	(11.70)%

Distributions ⁴
Total Distributions per share for the period	$0.45
Distribution Rate at NAV	6.60%
Distribution Rate at Market Price	7.47

% Total Leverage⁵
Auction Preferred Shares (APS)	4.89%
Borrowings	23.74

Growth of $10,000

This graph shows the change in value of a hypothetical investment of $10,000 in the Fund for the period indicated. For comparison, the same investment is shown in the indicated index.

See Endnotes and Additional Disclosures in this report.

Table of Contents

Eaton Vance

Senior Income Trust

June 30, 2026

Fund Profile

Top 10 Issuers (% of total investments)¹
Eaton Vance Floating-Rate ETF	1.1%
Allied Universal Holdco LLC	0.9
Asurion LLC	0.8
Benefit Street Partners CLO 48 Ltd.	0.7
Ballyrock CLO Ltd.	0.7
Ballyrock CLO 31 Ltd.	0.7
EOC Borrower LLC	0.7
TransDigm, Inc.	0.7
RR 27 Ltd.	0.7
Bryant Park Funding Ltd.	0.7
Total	7.7%

Top 10 Industries (% of total investments)¹
Software	8.6%
Health Care Providers & Services	6.9
Machinery	5.1
Commercial Services & Supplies	4.4
Capital Markets	4.4
Professional Services	4.3
Hotels, Restaurants & Leisure	3.8
Insurance	3.1
Trading Companies & Distributors	2.7
Entertainment	2.6
Total