SEC Form 4 · accession 0000310354-26-000074

· SXI

Statement of changes in beneficial ownership, as filed. Original on EDGAR ↗

Reporting owner

David A. Dunbar

Officer — President/CEO/Chairman · Director

Period of report

Aug 21, 2026

Accepted (ET)

Aug 25, 2026 · 5:13 pm EDT

Rule 10b5-1 plan

box not checked

Issuer CIK

0000310354

Table I — non-derivative securities

Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1	Aug 21, 2026	M	4,441	—	A	5,871	D
Common Stock	Aug 21, 2026	F	1,644	$310.28	D	4,227	D
Common Stock^F3	Aug 21, 2026	M	7,208	—	A	11,435	D
Common Stock	Aug 21, 2026	F	2,837	$310.28	D	8,598	D
Common Stock^F4	Aug 21, 2026	M	2,300	—	A	10,898	D
Common Stock	Aug 21, 2026	F	851	$310.28	D	10,047	D
Common Stock^F4	Aug 21, 2026	M	2,076	—	A	12,123	D
Common Stock	Aug 21, 2026	F	817	$310.28	D	11,306	D
Common Stock	holding	—	—		—	88,973	I	Trustee of Trust

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	Owned after	D/I
Phantom Stock Units^F1	$106.10	Aug 21, 2026	M	4,441	D	Aug 23, 2026	Aug 23, 2026	Common Stock	4,441	0	D
Phantom Stock Units^F3	—	Aug 21, 2026	M	7,208	D	Aug 23, 2026	Aug 23, 2026	Common Stock	7,208	3,393	D
Phantom Stock Units^F5	—	Aug 21, 2026	D	3,393	D	Aug 23, 2026	Aug 23, 2026	Common Stock	3,393	0	D
Restricted Stock Units^F4	—	Aug 21, 2026	M	2,300	D	—	—	Common Stock	2,300	2,300	D
Restricted Stock Units^F4	—	Aug 21, 2026	M	2,076	D	—	—	Common Stock	2,076	4,152	D
Phantom Stock Units^F6	—	Aug 23, 2026	A	2,285	A	Aug 23, 2029	Aug 23, 2029	Common Stock	2,285	2,285	D
Phantom Stock Units^F7	—	Aug 23, 2026	A	7,156	A	Aug 23, 2029	Aug 23, 2029	Common Stock	7,156	7,156	D
Restricted Stock Units^F8	—	Aug 23, 2026	A	4,770	A	—	—	Common Stock	4,770	4,770	D
Stock Option^F9	$341.31	Aug 23, 2026	A	32,600	A	—	—	Common Stock	32,600	32,600	D

Explanation of responses

F1Vesting of Phantom Stock pursuant to Company's Management Stock Purchase Plan.
F2Shares sold to pay taxes on vesting of previously issued restricted stock and/or performance share units.
F3Vesting of Phantom Stock pursuant to the Company's 2018 Omnibus Incentive Plan. Actual achievement, which could have ranged from 0% to 250% of the award, was 68%. The transaction reported herein is the actual number of shares vesting pursuant thereto.
F4Vesting of Restricted Stock Units pursuant to the Company's 2018 Omnibus Incentive Plan.
F5Vesting of Phantom Stock pursuant to the Company's 2018 Omnibus Incentive Plan. Actual achievement, which could have ranged from 0% to 250% of the award, was 68%. Phantom Stock Units were granted at 100% achievement, so this transaction reflects the disposition of shares to accurately reflect the vesting.
F6Contingent Purchase of Phantom Stock of the Company pursuant to the Management Stock Purchase Plan component of the 2018 Omnibus Incentive Plan vesting three years after the date of purchase in the form of Common Stock.
F7Award of Performance Share Units pursuant to the 2018 Omnibus Incentive Plan of the Company. These shares cliff vest at the end of a three year performance period with the ultimate number of shares ranging from 0 to 250% of the award based on achievement against Company performance metrics of the three year period.
F8Grant of Restricted Stock Units pursuant to the 2018 Omnibus Incentive Plan of the Company which vests one-third per year on each anniversary of the date of the award.
F9Premium Priced Stock Option with exercise price 10% above the closing market price on the date of grant. Option vests 25% per year on each anniversary of the date of the award for four years. This option expires ten years from the date of grant.