Pollution Control Equipment

Donaldson Company Inc. vs Madison Air Solutions Corporation

Short historyDCI / MAIRPrices through Oct 22, 2026

Why these are rivals: #1 and #2 by market value ($12B vs $10B) in Nasdaq's "Pollution Control Equipment" industry; SEC SIC 3564 / 3564 (same major group); #1 and #2 by market value ($12B vs $10B) with SEC SIC 3564 (Industrial & Commercial Fans & Blowers & Air Purifing Equip).

Less than a year of shared trading history, so no relationship can be measured yet.

Aligned sessions: 132 (needs >= 254)

Business leadership

Business size

Annual revenue reported to the SEC. Scale, not market share.

Year	DCI	MAIR	Larger
2025	$3.7B	-	-
2024	$3.6B	-	-
2023	$3.4B	-	-
2022	$3.3B	-	-
2021	$2.9B	-	-
2020	$2.6B	-	-

Market value: DCI $10.1B, MAIR $11.6B.

Stock leadership

Neither is clearly ahead

Measured against the pair's own last 252 trading days.

No statistic yet.

Price change	3 mo	6 mo	12 mo
DCI	-7.2%	-2.1%	-
MAIR	-33.5%	-32.6%	-

Relationship

Not a measured twin today

Only these tests can make a pair tradable on paper.

Fail: Aligned sessions: 132 (needs >= 254)
Data: Both stocks current

The twins over two years

Prices side by side, and the gap between them

DCI Donaldson Company Inc. MAIR Madison Air Solutions CorporationPrice index, 100 = 2026-04-16. Tint = which stock is ahead of the pair's usual 1-year relationship (z beyond +/-0.5).

Spread z-score: DCI relative to MAIR, against the 252 sessions before each day. Above 0: DCI ahead; below 0: MAIR ahead. Lines at +/-2 (idea) and +/-4 (stop).

Data table (132 sessions)

Date	DCI index	MAIR index	z
2026-10-22	98.57	72.69	n/a
2026-10-21	101.47	73.13	n/a
2026-10-20	100.26	73.04	n/a
2026-10-19	99.94	73.01	n/a
2026-10-16	100.69	73.51	n/a
2026-10-15	100.46	73.92	n/a
2026-10-14	99.82	73.32	n/a
2026-10-13	99.76	75.84	n/a
2026-10-12	98.97	73.35	n/a
2026-10-09	99.50	76.28	n/a
2026-10-08	99.76	75.59	n/a
2026-10-07	99.87	75.97	n/a
2026-10-06	103.14	77.48	n/a
2026-10-05	102.08	78.65	n/a
2026-10-02	101.47	78.87	n/a
2026-10-01	100.45	76.57	n/a
2026-09-30	99.62	77.48	n/a
2026-09-29	99.93	78.39	n/a
2026-09-28	100.13	78.65	n/a
2026-09-25	100.05	79.24	n/a
2026-09-24	99.12	76.76	n/a
2026-09-23	99.28	79.56	n/a
2026-09-22	98.49	78.90	n/a
2026-09-21	98.51	76.00	n/a
2026-09-18	98.94	75.62	n/a
2026-09-17	98.49	74.71	n/a
2026-09-16	98.81	73.95	n/a
2026-09-15	99.65	75.28	n/a
2026-09-14	100.64	74.52	n/a
2026-09-11	102.15	79.40	n/a
2026-09-10	100.93	78.46	n/a
2026-09-09	102.79	78.96	n/a
2026-09-08	104.14	82.33	n/a
2026-09-04	104.19	81.57	n/a
2026-09-03	103.70	80.88	n/a
2026-09-02	102.91	80.85	n/a
2026-09-01	102.74	81.10	n/a
2026-08-31	104.03	83.15	n/a
2026-08-28	105.17	82.93	n/a
2026-08-27	105.77	85.57	n/a
2026-08-26	109.01	89.80	n/a
2026-08-25	106.74	88.16	n/a
2026-08-24	105.79	78.65	n/a
2026-08-21	106.73	81.86	n/a
2026-08-20	105.80	82.68	n/a
2026-08-19	106.21	88.38	n/a
2026-08-18	107.55	86.43	n/a
2026-08-17	108.37	93.13	n/a
2026-08-14	109.82	98.52	n/a
2026-08-13	109.55	99.65	n/a
2026-08-12	110.19	100.31	n/a
2026-08-11	110.92	100.41	n/a
2026-08-10	110.72	95.53	n/a
2026-08-07	112.86	97.92	n/a
2026-08-06	112.56	98.46	n/a
2026-08-05	111.31	99.87	n/a
2026-08-04	112.33	100.00	n/a
2026-08-03	109.90	91.91	n/a
2026-07-31	107.86	91.53	n/a
2026-07-30	106.05	91.78	n/a
2026-07-29	105.87	99.65	n/a
2026-07-28	109.15	101.48	n/a
2026-07-27	106.66	108.82	n/a
2026-07-24	106.20	109.39	n/a
2026-07-23	104.31	114.24	n/a
2026-07-22	104.11	112.82	n/a
2026-07-21	103.22	112.13	n/a
2026-07-20	102.60	108.91	n/a
2026-07-17	103.47	107.09	n/a
2026-07-16	104.28	107.65	n/a
2026-07-15	102.17	106.87	n/a
2026-07-14	102.70	111.31	n/a
2026-07-13	102.19	111.34	n/a
2026-07-10	102.14	115.31	n/a
2026-07-09	101.32	112.79	n/a
2026-07-08	100.35	108.19	n/a
2026-07-07	102.48	109.73	n/a
2026-07-06	104.58	119.40	n/a
2026-07-02	101.97	117.10	n/a
2026-07-01	101.32	118.83	n/a
2026-06-30	102.75	122.83	n/a
2026-06-29	101.18	117.04	n/a
2026-06-26	101.32	118.39	n/a
2026-06-25	101.99	125.98	n/a
2026-06-24	98.51	124.09	n/a
2026-06-23	96.88	119.87	n/a
2026-06-22	98.37	121.45	n/a
2026-06-18	97.88	120.09	n/a
2026-06-17	97.69	117.92	n/a
2026-06-16	99.34	120.16	n/a
2026-06-15	98.92	122.52	n/a
2026-06-12	98.89	122.90	n/a
2026-06-11	97.73	126.80	n/a
2026-06-10	95.64	117.83	n/a
2026-06-09	98.62	127.75	n/a
2026-06-08	96.12	124.69	n/a
2026-06-05	95.74	126.43	n/a
2026-06-04	96.20	136.69	n/a
2026-06-03	97.56	137.20	n/a
2026-06-02	98.02	135.78	n/a
2026-06-01	93.61	138.14	n/a
2026-05-29	93.70	136.91	n/a
2026-05-28	95.40	133.01	n/a
2026-05-27	95.82	132.88	n/a
2026-05-26	97.01	134.93	n/a
2026-05-22	95.75	126.11	n/a
2026-05-21	94.56	122.11	n/a
2026-05-20	94.94	117.26	n/a
2026-05-19	93.34	121.48	n/a
2026-05-18	94.38	120.82	n/a
2026-05-15	93.79	129.13	n/a
2026-05-14	95.96	133.89	n/a
2026-05-13	96.06	133.86	n/a
2026-05-12	97.12	129.35	n/a
2026-05-11	97.96	132.54	n/a
2026-05-08	98.43	132.35	n/a
2026-05-07	98.33	132.91	n/a
2026-05-06	100.33	124.79	n/a
2026-05-05	98.75	124.57	n/a
2026-05-04	97.49	124.03	n/a
2026-05-01	98.68	126.52	n/a
2026-04-30	100.92	120.25	n/a
2026-04-29	99.58	113.39	n/a
2026-04-28	100.57	108.98	n/a
2026-04-27	102.77	108.88	n/a
2026-04-24	101.82	106.55	n/a
2026-04-23	100.69	107.84	n/a
2026-04-22	98.83	109.10	n/a
2026-04-21	101.18	106.46	n/a
2026-04-20	101.93	106.02	n/a
2026-04-17	102.09	102.20	n/a
2026-04-16	100.00	100.00	n/a

No one-day company-specific move of 4+ standard deviations in this window. Upcoming earnings: MAIR Oct 29, 2026 (not-supplied).

Paired trades

The shared paper book and the replay, kept apart

Forward paper record

No paper position on this pair yet.

Historical simulation (a diagnostic, same rules)

No simulated trade through Oct 20, 2026: the pair rarely passed every test while 2 standard deviations apart.

Per $10,000 a leg. A replay on today's companies cannot prove an edge.

The companies

DCI and MAIR at a glance

DCI Donaldson Company Inc.

Listing: NYSE · SEC CIK 29644
Industry: Pollution Control Equipment · SIC 3564 Industrial & Commercial Fans & Blowers & Air Purifing Equip
Market value: $10.1B
Price history: 2,521 daily closes, Oct 12, 2016 to Oct 22, 2026

MAIR Madison Air Solutions Corporation

Listing: NYSE · SEC CIK 2098430
Industry: Pollution Control Equipment · SIC 3564 Industrial & Commercial Fans & Blowers & Air Purifing Equip
Market value: $11.6B
Price history: 132 daily closes, Apr 16, 2026 to Oct 22, 2026

Daily prices: Nasdaq.com. Filings and industry codes: SEC EDGAR. Earnings dates: Nasdaq earnings calendar.

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Paper only: hypothetical paired positions with modelled costs. No broker, no orders, no real money. A historical simulation is a diagnostic, not proof of an edge. Not investment advice.