Southwest Airlines Co. (LUV) — Reincorporation detail

Announcement

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First SEC disclosure

Meeting / Vote

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TX_INCUMBENT_21_552_ADOPTER

Effective

—

Legal effective date

Market Cap

$18.0B

At announcement

Why this firm matters

Mid-to-large-cap firm ($18.0B) with sufficient market depth for reliable event-study identification.

Controller & ownership

Diffuse / non-controlled

Diffuse institutional + activist (Elliott Investment Management) holds approximately 9.6% of voting power. No single holder reaches the controlled-company threshold (>50% of voting power).

Source: DEF 14A 2026 (filed 2026-03-27); Schedule 13G/A filings

Vote outcome — reincorporation proposal

Approval standard: Board approval; bylaws amendment under TBOC §21.057. Meeting type: annual.

Vote totals not yet pulled. Awaiting EDGAR Item 5.07.

Event-study abnormal returns — announcement window

Returns around the announcement date.

No announcement-window CARs available for this firm yet.

Event-study abnormal returns — vote window

Returns around the shareholder-vote (or written-consent) date.

No vote-window CARs available for this firm yet.

Long-run abnormal returns & pooled estimates

Buy-and-hold abnormal returns (1 / 3 / 6 / 12 months) and calendar-time portfolio alpha (CTE) post-effective.

No long-run / pooled estimates available for this firm yet — run phase5z_compute_longrun.py on Windows to populate (requires effective date ≥ 3 months ago).

Cohort-level robustness battery

Heckman selection-corrected ATE · Romano-Wolf step-down + BH FDR · pooled BHAR. This firm's reading is shown in context of the full cohort.

Heckman two-step selection correction (controlled-vs-widely-held)

Cohort ATE = +0.94% (SE = 7.06%, n = 2395) after correcting for controller-status selection (inverse Mills ratio = -0.062).

Romano-Wolf step-down + Benjamini-Hochberg FDR (n = 47)

This firm: per-firm adjusted p-values pending. Multiple-hypothesis correction is computed across the full cohort to control family-wise error rate at alpha = 0.05.

Pooled cohort BHAR (mover firms only)

BHAR_63d: mean = -5.60% (SE = 22.11%, n = 3, p = 0.499) · BHAR_126d: mean = +17.33% (SE = 41.17%, n = 3, p = 0.774)

See Cohort event study → for the full battery and forest plots.

Texas statutory-adoption event study (SB 29 dates & bylaw amendments)

Event-study readings around the SB 29 legislative milestones and this firm's §21.552 bylaw-amendment date. Each panel shows the day-0 abnormal return under multiple specifications, plus long-run BHAR. Run via 02_BESPOKE/statutory_events_runner.py.

LUV 21 552 next trade 2025 05 20T0 = 2025-05-20

Headline T0: next trading day after 8-K filing (after-market-close rule)

Specification	Day-0 AR	Inference
Market model (SPY benchmark) HEADLINE	+0.09%	Patell-z p-value = 0.964
Sector-augmented (SPY + JETS airline ETF)	+0.46%	Patell-z p-value = 0.785
Synthetic control (8-donor airline peer pool)	+0.20%	no inference
Robustness footnote: SPY + XLI	+0.15%	Patell-z p-value (footnote spec) = 0.939
Robustness footnote: SPY + USO	+0.08%	Patell-z p-value (footnote spec) = 0.967

Long-run BHAR after this event (1 / 3 / 6 / 12 months) â–¾

1 month vs SPY	-3.33%	n = 22 days
3 months vs SPY	-11.37%	n = 64 days
6 months vs SPY	-12.42%	n = 127 days

Alternative T0 specifications â–¾

T0_a_board_2025-05-16	+1.77%	p = 0.391
T0_b_filing_2025-05-19	-0.42%	p = 0.837
T0_c_next_trading_2025-05-20	+0.09%	p = 0.964

Cumulative abnormal returns by window â–¾

Window	n days	CAR	p
Day0	1 days	+0.09%	p = 0.964
CAR_-1_+1	3 days	-0.61%	p = 0.863
CAR_-2_+2	5 days	-0.64%	p = 0.888
CAR_-5_+5	11 days	+3.89%	p = 0.567
CAR_-10_+10	21 days	-0.19%	p = 0.984
Post_+0_+5	6 days	+2.30%	p = 0.647
Post_+0_+20	21 days	-4.77%	p = 0.611
Post_+0_+60	61 days	-12.78%	p = 0.424

Calendar-time portfolio alpha (post-event): annualized = +14.17% · t = +0.31 · p = 0.757 · n = 12 months

SB29 senate passage 2025 04 03T0 = 2025-04-03

Senate engrossment (RV#159); passage near-certain in Senate

Specification	Day-0 AR	Inference
Market model (SPY benchmark) HEADLINE	-6.18% ^***	Patell-z p-value = 0.005
Sector-augmented (SPY + JETS)	-2.96% ^*	approx Patell-z p-value (2-factor) = 0.076
Matched pair vs DAL (market-model-adjusted)	-1.48%	two-sided p-value = 0.610
Raw differential vs DAL	+1.48%	no inference

Long-run BHAR after this event (1 / 3 / 6 / 12 months) â–¾

1 month vs SPY	-0.77%	n = 21 days
3 months vs SPY	+1.84%	n = 63 days
6 months vs SPY	-11.44%	n = 126 days
12 months vs SPY	+9.63%	n = 252 days

SB29 house passage 2025 05 02T0 = 2025-05-02

House RV#1339; passage near-certain in both chambers (cleanest single-day milestone)

Specification	Day-0 AR	Inference
Market model (SPY benchmark) HEADLINE	+2.55%	Patell-z p-value = 0.220
Sector-augmented (SPY + JETS)	+0.10%	approx Patell-z p-value (2-factor) = 0.952
Matched pair vs DAL (market-model-adjusted)	-1.59%	two-sided p-value = 0.595
Raw differential vs DAL	-1.96%	no inference

Long-run BHAR after this event (1 / 3 / 6 / 12 months) â–¾

1 month vs SPY	+4.04%	n = 21 days
3 months vs SPY	-11.45%	n = 63 days
6 months vs SPY	-18.37%	n = 126 days

SB29 signed effective 2025 05 14T0 = 2025-05-14

Signed by Governor; effective immediately

Specification	Day-0 AR	Inference
Market model (SPY benchmark) HEADLINE	+0.11%	Patell-z p-value = 0.957
Sector-augmented (SPY + JETS)	+2.15%	approx Patell-z p-value (2-factor) = 0.199
Matched pair vs DAL (market-model-adjusted)	+4.92%	two-sided p-value = 0.107
Raw differential vs DAL	+4.94%	no inference

Long-run BHAR after this event (1 / 3 / 6 / 12 months) â–¾

1 month vs SPY	-0.49%	n = 21 days
3 months vs SPY	-11.69%	n = 63 days
6 months vs SPY	-9.51%	n = 126 days

LUV 21 552 board 2025 05 16T0 = 2025-05-16

Board adoption of Fifth Amended and Restated Bylaws (§21.552 election); 8-K acc 0000092380-25-000119

Specification	Day-0 AR	Inference
Market model (SPY benchmark) HEADLINE	+1.76%	Patell-z p-value = 0.394
Sector-augmented (SPY + JETS)	+1.54%	approx Patell-z p-value (2-factor) = 0.360
Matched pair vs DAL (market-model-adjusted)	+1.42%	two-sided p-value = 0.642
Raw differential vs DAL	+1.28%	no inference

Long-run BHAR after this event (1 / 3 / 6 / 12 months) â–¾

1 month vs SPY	-4.33%	n = 21 days
3 months vs SPY	-12.19%	n = 63 days
6 months vs SPY	-12.13%	n = 126 days

LUV 21 552 filing 2025 05 19T0 = 2025-05-19

8-K filed AFTER market close at 16:38:57 ET

Specification	Day-0 AR	Inference
Market model (SPY benchmark) HEADLINE	-0.40%	Patell-z p-value = 0.845
Sector-augmented (SPY + JETS)	-0.41%	approx Patell-z p-value (2-factor) = 0.807
Matched pair vs DAL (market-model-adjusted)	-0.84%	two-sided p-value = 0.783
Raw differential vs DAL	-0.77%	no inference

Long-run BHAR after this event (1 / 3 / 6 / 12 months) â–¾

1 month vs SPY	-4.27%	n = 21 days
3 months vs SPY	-10.39%	n = 63 days
6 months vs SPY	-13.70%	n = 126 days

Texas Statutory Adoptions

Texas opt-in statutory regimes available to Texas-incorporated public companies. Each requires a charter or bylaw amendment with proxy notice. Both are independently elected.

SB 29 — TBOC §21.552

Derivative-action 3% ownership threshold (effective 2025-05-14, post-Tornetta v. Musk).

âœ“ ADOPTED

Source: 8-K Item 5.03 [Filing â†—]

SB 1057 — TBOC §21.373

Shareholder-proposal threshold: lesser of $1M market value or 3% of voting shares, 6-month hold, 67% solicit (effective 2025-09-01). Director nominations and procedural resolutions are exempt. Legal status: vulnerable to challenge under the Internal Affairs Doctrine and dormant Commerce Clause; SEC Rule 14a-8(i)(1) permits state-law exclusion, so §21.373 may operate through Rule 14a-8 rather than face direct preemption. No court ruling has issued. Firms appear to be in a wait-and-see posture pending legal clarity.

PENDING VERIFICATION

Adoption is opt-in. A "No" or "Pending" status means the firm has not (yet) elected into the regime — it does not mean the firm is non-compliant. Adoption requires a charter/bylaw amendment disclosed via 8-K Item 5.03.

Source filings

Primary-source documents on SEC EDGAR plus IR / search links.

IR — https://www.southwestairlinesinvestorrelations.com/
EDGAR — https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0000092380&type=&dateb=&owner=include&count=40
Proxy — https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0000092380&type=DEF+14A&dateb=&owner=include&count=40
EDGAR accession (canonical) — 0000092380-25-000119

Classification & audit trail

Bucket

COMPARATOR_TX_INCUMBENT

Panel eligibility

PANEL_C_TX_INCUMBENT_ADOPTER

Audit status

VERIFIED_EDGAR

Source confidence

VERIFIED_PRIMARY_SOURCE

Transaction status

N/A

Audit notes

[2026-04-30] v3.84-rev5x: LUV added as a TX-INCUMBENT 21.552 ADOPTER comparator (distinct from the DE->TX migrator cohort). Bespoke event-study battery from 02_BESPOKE/LUV_TBOC_21552_Analysis/luv_event_study_results.json + bespoke statutory-events runner output. Board adoption 2025-05-16, 8-K filing 2025-05-19 (after market close), T0 headline 2025-05-20, accession 0000092380-25-000119, Items 3.03/5.03/9.01.
[2026-05-31 rev101 integrity-gate] panel_a_tx_incumbent 0→1. COMPARATOR_TX_INCUMBENT requires panel_a=1; data-integrity audit gate flagged the mismatch.
PATCHED_rev131-phase-a-tboc-21552-adopters-2026-06-04_phase_a: tboc_21_552_tier=TIER_1_EDGAR_VERIFIED acc=0000092380-25-000119