Main Street Capital CORP

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 thethird 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 thethird 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.