Exhibit 99.1

	NEWS RELEASE
	Contacts: Main Street Capital Corporation Dwayne L. Hyzak, CEO, dhyzak@mainstcapital.com Ryan R. Nelson, CFO, rnelson@mainstcapital.com 713-350-6000 Dennard Lascar Investor Relations Ken Dennard / ken@dennardlascar.com Zach Vaughan / zvaughan@dennardlascar.com 713-529-6600

Main Street Announces Preliminary Estimate of Third Quarter 2026

Operating Results

Announces Third Quarter 2026 Earnings Release and Conference Call Schedule

HOUSTON – October 15, 2026 – Main Street Capital Corporation (NYSE: MAIN) (“Main

Street” or the “Company”) is pleased to announce its preliminary operating results for the third

quarter of 2026 and its third quarter 2026 earnings release and conference call schedule.

In commenting on the Company’s preliminary operating results for the third quarter of 2026,

Dwayne L. Hyzak, Main Street’s Chief Executive Officer, stated, “We are pleased with our

performance in the third quarter, which resulted in another quarter of strong operating results,

including distributable net investment income before taxes that was in line with our expectations

and prior guidance provided on our last conference call and an increase to our net asset value per

share for the seventeenth consecutive quarter. We look forward to sharing the full details of our

third quarter 2026 results in a few weeks.”

Preliminary Estimates of Third Quarter 2026 Results

Main Street’s preliminary estimate of third quarter 2026 net investment income (“NII”) is $0.87

to $0.91 per share, distributable net investment income (“DNII”)(1) is $0.94 to $0.98 per share

and DNII before taxes(2) is $0.96 to $1.00 per share.

Main Street’s preliminary estimate of net asset value (“NAV”) per share as of September 30,

2026 is $34.18 to $34.26, representing an increase of $0.26 to $0.34 per share, or 0.8% to 1.0%,

from the NAV per share of $33.92 as of June 30, 2026, with this increase after the impact of the

supplemental dividend paid in September 2026 of $0.30 per share. The estimated NAV per share

increase is primarily due to the net fair value appreciation on the investment portfolio, including

realized and unrealized activity, and the accretive impact of equity issuances, partially offset by

the total dividends per share paid in the third quarter in excess of NII per share and the net tax

provision. The net fair value appreciation on the investment portfolio is primarily the result of

net fair value appreciation on the lower middle market (“LMM”) investment portfolio, private

loan investment portfolio and other portfolio investments, partially offset by net fair value

depreciation on the middle market investment portfolio and fair value depreciation of the wholly-

owned external investment manager.

As a result of Main Street’s preliminary estimates of NII, net fair value appreciation and the net

tax provision as noted above, Main Street estimates that it generated an annualized return on

equity of over 14% for the third quarter.(3)

Main Street preliminarily estimates that investments on non-accrual status comprised 0.9% of the

total investment portfolio at fair value and 3.5% at cost as of September 30, 2026.

Additionally, during the quarter, Main Street Mezzanine Fund, LP, an investment fund wholly-

owned by the Company and licensed as a Small Business Investment Company (“SBIC”) by the

U.S. Small Business Administration (“SBA”), received approval from the SBA to increase the

borrowing capacity of its SBIC debentures by $75.0 million to $250.0 million. Combined with

Main Street’s other wholly-owned investment fund licensed as an SBIC, Main Street Capital III,

LP, this gives Main Street access to $425.0 million of the recently increased $475.0 million of

regulatory maximum SBIC debenture borrowing capacity for affiliated SBIC funds. Main Street

expects to maintain SBIC debentures under the SBIC program in the future, subject to periodic

repayments and borrowings, in an amount up to the regulatory maximum amount.

Investment Portfolio Activity

The Company’s third quarter 2026 operating activities include the following investment activity

in the LMM and private loan investment strategies:

•$61.5 million in total LMM portfolio investments, which after aggregate repayments,

return of invested equity capital and a decrease in cost basis due to a realized loss resulted

in a net decrease of $19.4 million in the total cost basis of the LMM investment portfolio;

and

•$162.0 million in total private loan portfolio investments, which after aggregate

repayments, return of invested equity capital and a decrease in cost basis due to realized

losses resulted in a net decrease of $1.8 million in the total cost basis of the private loan

investment portfolio.

Third Quarter 2026 Earnings Release and Conference Call Schedule

Main Street will release its third quarter 2026 results on Thursday, November 5, 2026, after the

financial markets close. In conjunction with the release, Main Street has scheduled a conference

call, which will be broadcast live via phone and over the Internet, on Friday, November 6, 2026,

at 10:00 a.m. Eastern time. Investors may participate either by phone or audio webcast.(4)

By Phone:	Dial 412-902-0030 at least 10 minutes before the call. A replay will be available through November 13, 2026 by dialing 201-612-7415 and using the access code 13762919#.
By Webcast:	Connect to the webcast via the Investor Relations section of Main Street’s website at www.mainstcapital.com. Please log in at least 10 minutes in advance to register and download any necessary software. A replay of the conference call will be available on Main Street’s website shortly after the call and will be accessible until the date of Main Street’s earnings release for the next quarter.

ABOUT MAIN STREET CAPITAL CORPORATION

Main Street (www.mainstcapital.com) is a principal investment firm that primarily provides

customized long-term debt and equity capital solutions to lower middle market companies and

debt capital to private companies owned by or in the process of being acquired by a private

equity fund. Main Street’s portfolio investments are typically made to support management

buyouts, recapitalizations, growth financings, refinancings and acquisitions of companies that

operate in diverse industry sectors. Main Street seeks to partner with entrepreneurs, business

owners and management teams and generally provides customized “one-stop” debt and equity

financing solutions within its lower middle market investment strategy. Main Street seeks to

partner with private equity fund sponsors and primarily invests in secured debt investments in its

private loan investment strategy. Main Street’s lower middle market portfolio companies

generally have annual revenues between $10 million and $150 million. Main Street’s private

loan portfolio companies generally have annual revenues between $25 million and $500 million.

Main Street, through its wholly-owned portfolio company MSC Adviser I, LLC dba Main Street

Capital Partners (“MSCP Adviser”), also maintains an asset management business through which

it manages investments for external parties. MSCP Adviser is registered as an investment adviser

under the Investment Advisers Act of 1940, as amended.

FORWARD-LOOKING STATEMENTS AND OTHER MATTERS

Main Street cautions that statements in this press release which are forward-looking and provide

other than historical information, including but not limited to the preliminary estimates of third

quarter 2026 financial information and results, are based on current conditions and information

available to Main Street as of the date hereof. Although its management believes that the

expectations reflected in those forward-looking statements are reasonable, Main Street can give

no assurance that those expectations will prove to be correct. Those forward-looking statements

are made based on various underlying assumptions and are subject to numerous uncertainties and

risks, including, without limitation, such factors described under the captions “Cautionary

Statement Concerning Forward-Looking Statements” and “Risk Factors” included in Main

Street’s filings with the U.S. Securities and Exchange Commission (the “SEC”) (www.sec.gov).

Main Street undertakes no obligation to update the information contained herein to reflect

subsequently occurring events or circumstances, except as required by applicable securities laws

and regulations.

The preliminary estimates of third quarter 2026 financial information and results furnished above

are based on Main Street management’s preliminary determinations and current expectations,

and such information is inherently uncertain. The preliminary estimates provided herein have

been prepared by, and are the responsibility of, management and are subject to completion of

Main Street’s customary quarter-end closing and review procedures and third-party review,

including the determination of the fair value of Main Street’s portfolio investments. As a result,

actual results could differ materially from the current preliminary estimates based on adjustments

made during Main Street’s quarter-end closing and review procedures and third-party review,

and Main Street’s reported information in its Quarterly Report on Form 10-Q for the quarter

ended September 30, 2026 may differ from this information, and any such differences may be

material. In addition, the information furnished above does not include all of the information

regarding Main Street’s financial condition and results of operations for the quarter ended

September 30, 2026 that may be important to readers. As a result, readers are cautioned not to

place undue reliance on the information furnished in this press release and should view this

information in the context of Main Street’s full third quarter 2026 results when such results are

disclosed by Main Street in its Quarterly Report on Form 10-Q for the quarter ended

September 30, 2026. The information furnished in this press release is based on Main Street

management’s current expectations that involve substantial risks and uncertainties that could

cause actual results to differ materially from the results expressed in, or implied by, such

information.

Main Street has an existing effective Registration Statement on Form N-2 on file with the SEC

relating to the offer and sale from time to time of its securities. Investors are advised to carefully

consider the investment objective, risks and charges and expenses of Main Street before

investing in any of Main Street’s securities. The prospectus included in the Registration

Statement on Form N-2, together with any related prospectus supplement, contain this and other

information about Main Street and should be read carefully before investing. A copy of the

prospectus and any related prospectus supplement may be obtained by contacting Main Street.

Endnotes

(1)DNII is NII as determined in accordance with U.S. Generally Accepted Accounting

Principles, or U.S. GAAP, excluding the impact of non-cash compensation expenses,

which includes both share-based compensation expenses and deferred compensation

expense or benefit. Main Street believes presenting DNII per share is useful and

appropriate supplemental disclosure for analyzing its financial performance since (i)

share-based compensation does not require settlement in cash and (ii) deferred

compensation expense or benefit does not result in a net cash impact to Main Street

upon settlement. However, DNII is a non-U.S. GAAP measure and should not be

considered as a replacement for NII or other earnings measures presented in

accordance with U.S. GAAP. Instead, DNII should be reviewed only in connection

with such U.S. GAAP measures in analyzing Main Street’s financial performance. In

order to reconcile estimated DNII per share to estimated NII per share in accordance

with U.S. GAAP for the third quarter of 2026, an estimated $0.06 to $0.07 per share

of non-cash compensation expenses are added back to estimated NII per share to

calculate estimated DNII per share.

(2)DNII before taxes is NII as determined in accordance with U.S. GAAP, excluding the

impact of non-cash compensation expenses, which includes both share-based

compensation expenses and deferred compensation expense or benefit, and any tax

expenses included in NII. Main Street believes presenting DNII before taxes per share

is useful and appropriate supplemental disclosure for analyzing its financial

performance since (i) share-based compensation does not require settlement in cash,

(ii) deferred compensation expense or benefit does not result in a net cash impact to

Main Street upon settlement and (iii) tax expenses included in NII may include (a)

excise tax expense, which is not solely attributable to NII, and (b) deferred taxes,

which are not payable in the current period. However, DNII before taxes is a non-

U.S. GAAP measure and should not be considered as a replacement for NII, NII

before taxes or other earnings measures presented in accordance with U.S. GAAP.

Instead, DNII before taxes should be reviewed only in connection with such U.S.

GAAP measures in analyzing Main Street’s financial performance. In order to

reconcile estimated DNII before taxes per share to estimated NII per share in

accordance with U.S. GAAP for the third quarter of 2026, an estimated $0.06 to

$0.07 per share of non-cash compensation expenses and an estimated $0.02 per share

of NII related tax expenses are added back to estimated NII per share to calculate

estimated DNII before taxes per share.

(3)Return on equity equals the net increase in net assets resulting from operations

divided by the average quarterly total net assets.

(4)No information contained on the Company’s website or disclosed on the November 6,

2026 conference call, including the webcast and the archived versions, is incorporated

by reference in this press release or any of the Company’s filings with the SEC, and

you should not consider that information to be part of this press release or any other

such filing.