Dropbox, Inc. (DBX) — Reincorporation detail

Why this firm matters

Standard cohort firm (Completed). Included for breadth across destinations and sectors.

Controller & ownership

CONTROLLED COMPANYFounder Supervoting Class

Drew Houston (Co-founder/CEO, via Class B 10:1 supervoting) holds approximately 78.7% of voting power. This firm meets the strict listing-rule controlled-company threshold (controller holds >50% of voting power per NYSE Rule 303A.00 / Nasdaq Rule 5615(c)).

Source: DBX 2025 DEF 14A (annual meeting May 15, 2025, accession 0001467623-25-000047) + Houston Schedule 13G/A (Dec 31, 2024, amended March 31, 2026) — Houston beneficially owns ~76.6M Class B + 8.27M Class A directly + trusts; 214.1M Class A + 76.9M Class B outstanding; Class B carries 10 votes/share; combined voting power (8.27M + 76.6M×10) / (214.1M + 76.9M×10) = 774.3M / 983.3M = 78.7%. Note: ~80 Class B stockholders total; Houston is the majority holder. Controlled company under NYSE Rule 303A.00 (>50% voting power). Tracker's prior ~80% ESTIMATED figure refined to 78.7% precise. Corrected 2026-05-19 via Tier-3 overnight reviewer dispatch.

Vote outcome — reincorporation proposal

Approval standard: majority of voting power of outstanding shares entitled to vote (written consent under DGCL §228 or state equivalent). Meeting type: annual.

Vote totals not yet pulled. Awaiting EDGAR Item 5.07.

Visual evidence — event study around the announcement

Per-firm event-study figures auto-built from event_study_announcement_json in the master database. Each panel is generated deterministically from the same data backing the cohort statistics — no firm-specific tuning, no cherry-picking.

Dropbox's announcement-day move was a non-event

**Bottom line.** All four ways of looking at Dropbox's stock that day point to roughly the same answer: rose modestly by about 0.7%, and the move was statistically indistinguishable from a normal trading day (p = 0.74).

This chart shows four different statistical lenses on what Dropbox's stock did on the day the reincorporation was announced. Each lens compares the actual move against a different prediction of what "normal" should have looked like — peer firms, the broader market, a single matched competitor, or a raw side-by-side. The gold-edged bar marks the lens used in the cohort summary.

Method

Specifications: synthetic control on a sector peer pool, single-factor market model (S&P 500 benchmark), matched pair against a pre-specified primary peer, and raw differential. Estimation window: 240 trading days ending the day before the announcement. Standard errors via Patell-z (1976).

Dropbox sits near the middle of the 36-firm cohort

**Bottom line.** Dropbox's announcement-day reading is close to the cohort-wide mean of +0.69%. Most firms in this cohort moved by similar small amounts; reactions are firm-specific, not regime-specific.

This chart shows every firm in the cohort that has a computed announcement-day abnormal return — sorted from largest negative to largest positive. Dropbox is highlighted in gold. The dashed line marks the cohort-wide average, which is essentially zero. Even firms in the same destination state and same statutory regime can have very different reactions.

Method

Same headline-specification methodology applied to every firm in the 36-firm cohort that has 240 trading days of pre-announcement price history.

Data integrity. All figures generated by the same script (perfirm_gallery.py) on every release; SHA-256 verified at deploy time. See also: Cohort-wide event study →.

Event-study abnormal returns — announcement window

Returns around the announcement date.

Event date: 2025-01-31 · Estimation window: 2024-02-15 to 2025-01-30 (240 days)

Specification	Day-0 AR	Inference
Synthetic control (9-donor Information Technology peer pool)i	-0.31%	no inference
Market model (SPY benchmark)i	+0.60%	Patell-z p-value = 0.776
Sector-augmented model (SPY + Nasdaq-100 (QQQ)) HEADLINEi	+0.70%	Patell-z p-value = 0.739
Matched pair (vs BOX, market-model-adjusted)i	-0.05%	two-sided p-value = 0.984
Raw differential vs BOXi	-0.42%	no inference

Robustness checks — does the headline result hold up?

Three independent diagnostics that interrogate the headline estimate from different angles. All three pointing the same way = high confidence in the result.

Pre-event drift check: the firm's daily abnormal return drifted by +0.0050% per day in the pre-event window (p = 0.013). pretrend detected. — A near-zero slope means the pre-event period was stable, so the day-0 reaction is not contamination from a pre-existing trend.
Donor co-movement check: 5 of 9 peer firms moved in the same direction as the treated firm on the event day (binomial p = 1.0000). — A high concordance means the day was driven by industry-wide news rather than something firm-specific. A low concordance means the firm moved differently from peers (potential firm-specific signal).
Synthetic-control fit quality: pre-event correlation between the firm and its synthetic twin = 0.842 (good tracking); R² = -5.791 (fraction of pre-event variance explained); Durbin-Watson = 2.00 (no autocorrelation). — Higher correlation + higher R² + Durbin-Watson near 2 means the synthetic peer was a good match before the event, so the post-event gap is interpretable.

Event-study abnormal returns — vote window

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

Event date: 2025-03-05 · T0 source: actual_effective_date_iso · Estimation window: trailing 240 days; 240 valid after NaN drop

Specification	Day-0 AR	Inference
Market model (SPY benchmark) HEADLINEi	-1.05%	Patell-z p-value = 0.548

Long-run abnormal returns & pooled estimates

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

Effective date: 2025-03-05 · n_post = 290 days

Buy-and-hold abnormal returns (BHAR)

Horizon & benchmark	BHAR	Inference
1 month vs S&P 500	+9.61%	Patell-z = +1.25 · p = 0.210 · n = 21 days
1 month vs sector ETF (XLK)	+13.67%	Patell-z = +1.25 · p = 0.210 · n = 21 days
3 months vs S&P 500	+8.43%	Patell-z = +0.91 · p = 0.361 · n = 63 days
3 months vs sector ETF (XLK)	+3.88%	Patell-z = +0.91 · p = 0.361 · n = 63 days
6 months vs S&P 500	-0.18%	Patell-z = +0.67 · p = 0.504 · n = 126 days
6 months vs sector ETF (XLK)	-7.12%	Patell-z = +0.67 · p = 0.504 · n = 126 days
12 months vs S&P 500	-14.89%	Patell-z = +0.60 · p = 0.551 · n = 252 days
12 months vs sector ETF (XLK)	-22.91%	Patell-z = +0.60 · p = 0.551 · n = 252 days

Calendar-time portfolio alpha (CTE)

Specification	Annualized alpha	Inference
Calendar-time portfolio alpha vs S&P 500	-18.43%/yr	t = -0.93 · p = 0.351 · n = 290 days · Newey-West HAC SE (lag=5)
Calendar-time portfolio alpha vs sector ETF	-19.23%/yr	t = -0.95 · p = 0.342 · n = 290 days · Newey-West HAC SE (lag=5)

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: raw p = 0.739, Romano-Wolf adjusted p = 1.000, BH-FDR adjusted p = 0.966. 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.

Source filings

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

IR — https://investors.dropbox.com/
EDGAR — https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0001467623&type=&dateb=&owner=include&count=40
Proxy — https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0001467623&type=DEF+14A&dateb=&owner=include&count=40
EDGAR accession (canonical) — 0001140361-25-003654

Classification & audit trail

Bucket

A

Panel eligibility

PRE_SB29_BENCHMARK

Audit status

VERIFIED_WRITTEN_CONSENT

Source confidence

VERIFIED_EFFECTIVE

Transaction status

COMPLETED

Audit notes

[2026-04-28] Phase 4I: replaced Google-search IR fallback with direct URL https://investors.dropbox.com/
[2026-04-28] Phase 4K: corrected mechanism (was implied meeting, actually WRITTEN CONSENT under founder-controlled dual-class structure). PRE 14C 2025-01-31; eff 2025-03-05 5:00pm PT. Removed phantom 2025-06-04 meeting date — that was unrelated annual meeting, not the reincorporation vote. Pre-SB29 NV benchmark.
[2026-04-28] Phase 4N: synthesized event_study_announcement_json from existing scalar CAR cells (phase4a_v2 join). Reviewer can extend with multi-spec analysis. [2026-04-28] phase5e: cleaned edgar_accession_canonical: extracted '0001140361-25-003654' from raw value '0001140361-25-003654 (DEF 14C effective Mar 5, 2025; Houston trust written consent)' (source=dashed) [2026-04-29] phase5g: WRITTEN_CONSENT — meeting_date_iso set to consent execution date 2025-01-28 (reviewer: https://www.sec.gov/Archives/edgar/data/1467623/000114036125002654/ny20042422x1_pre14c.htm) [2026-04-29] phase5g: vote_source set DEF 14C acc=0001140361-25-002654 url=https://www.sec.gov/Archives/edgar/data/1467623/000114036125002654/ny20042422x1_pre14c.htm (written-consent transaction; reviewer: https://www.sec.gov/Archives/edgar/data/1467623/000114036125002654/ny20042422x1_pre14c.htm) [2026-04-29] phase5g: WRITTEN_CONSENT — meeting_date_iso set to consent execution date 2025-01-28 (reviewer: https://www.sec.gov/Archives/edgar/data/1467623/000114036125002654/ny20042422x1_pre14c.htm) [2026-04-29] phase5g: vote_source set DEF 14C acc=0001140361-25-002654 url=https://www.sec.gov/Archives/edgar/data/1467623/000114036125002654/ny20042422x1_pre14c.htm (written-consent transaction; reviewer: https://www.sec.gov/Archives/edgar/data/1467623/000114036125002654/ny20042422x1_pre14c.htm) [2026-04-29] phase5m: DBX vote_mechanism already=WRITTEN_CONSENT; Item 8.01 8-K confirms reincorporation effective March 5, 2025 at 5:00pm PT, written consent of stockholders Jan 28, 2025 per board recommendation; primary source: Form 8-K filed March 10, 2025 (Item 8.01 Other Events); user-provided IR URL: https://dropbox.gcs-web.com/node/12371/html [2026-04-29] phase5r: bucket 'B2' -> 'A' (DE->NV effective 2025-03-05 < SB29 (2025-05-14) -> bucket A (pre-SB29)) [2026-04-29] phase5w: comprehensive validation by external reviewer across tranches v4 (4-version full residual walk, 269 substantive answers across 52 firms, 0 bucket drifts vs v3.58)
[2026-04-29] v3.75: written-consent transaction; approval_pct NULL by design per protocol §3.7. Standard derived from DGCL §228. Per-firm consent threshold pincite pending PRE 14C / 8-K review.