Analysis: Markwayne Mullin's purchase of COST (Costco Wholesale Corp)

Assessment: On watch

Routine year-end rebalancing into a blue-chip retailer with no identifiable policy catalyst.

Member: Markwayne Mullin
Party / state: R-OK
Chamber: Senate
Transaction: Purchase
Amount: $15,001 - $50,000
Ticker: COST
Company: Costco Wholesale Corp
Trade date: 2025-12-29
Disclosure date: 2026-01-16
Disclosure lag: 18 days

Executive summary

Senator Markwayne Mullin, a member of the Senate Appropriations and HELP committees, executed a $15,001-$50,000 purchase of Costco (COST) on December 29, 2025. This trade was part of a broader end-of-year buying spree where the Senator initiated or added to positions in over 10 high-cap tickers including MSFT, AMZN, and META.

The COST purchase appears to be part of a systematic rebalancing or capital deployment strategy rather than an isolated, catalyst-driven event. On the same day (2025-12-29), Mullin purchased significant amounts of GS, AMAT, LRCX, CVX, MSFT, COP, LLY, AMZN, and META. The COST purchase is consistent with his historical 'buy-and-hold' pattern for this ticker, as he has not recorded a sale of COST since his first purchase in September 2023. While Mullin sits on the HELP committee which oversees labor, there is no immediate evidence of pending specific legislation or hearings targeting Costco in the 30-day window surrounding the trade. The trade occurred at a price of $867.84, significantly lower than the $915-$936 range seen in trades by other members in late 2025, suggesting a 'buy the dip' entry during a period of moderate market volatility.

Timeline

2025-11-10 — Ro Khanna purchases COST shares.
2025-12-24 — Gilbert Cisneros sells COST shares.
2025-12-29 — Markwayne Mullin purchases COST ($15k-$50k).
2026-01-16 — Trade disclosed to Senate Office of Public Records.

Independent analysis of public financial disclosures. Not financial or investment advice.

Sources

Markwayne Mullin · COST · Trading news