HRT Financial LP, a 10%+ owner of United States Oil Fund, LP (USO), added another leg to its ongoing buying campaign on September 16, 2026, purchasing 14,291 shares at $154.57 apiece for a total outlay of $2,208,959.87. The open-market purchase — meaning HRT used its own capital rather than exercising options or receiving a grant — brings the firm’s directly held stake to 128,543 shares.
This latest trade is not an isolated event. According to Form 4 filings, HRT Financial has now made 11 separate open-market purchases of USO shares between September 11 and September 16, 2026, with a combined value of $23,385,361. The size and frequency of these purchases place the activity squarely in the category our site classifies as a cluster buy: a concentrated series of insider purchases within a short window, rather than a single one-off transaction.
A Pattern That Keeps Growing
We flagged this behavior earlier in the run. As detailed in our previous coverage, HRT Financial’s $16.6M USO Buying Spree: Inside the Cluster, the firm had already accumulated over $16 million in USO purchases by mid-September. The September 16 transaction adds nearly $2.21 million more to that running total, pushing the cumulative figure past $23.3 million in less than a week.
Each individual filing shows HRT building its position incrementally rather than in one large block trade, a pattern consistent with a fund steadily accumulating shares in the open market over multiple sessions at varying price points, including the $154.57 print recorded on this latest date.
Why Cluster Buys Draw Attention
Clustered insider buying — where a single insider or affiliated group makes repeated purchases over a compressed timeframe — has been studied by academic researchers as a signal that historically correlates with periods of subsequent outperformance in the underlying security, more so than isolated single purchases. This is offered here as historical context only; it is not a recommendation, and this filing should not be read as investment advice. HRT Financial’s classification as a 10%+ owner also means these purchases are subject to standard disclosure requirements under Section 16 of the Securities Exchange Act, giving the public visibility into the fund’s evolving position in USO in near real time.
With the 128,543-share direct stake now on record as of September 16, and the broader 11-transaction sequence still fresh, USO’s ownership filings will be worth watching for whether the pattern continues into the following week or has run its course.
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Source: original SEC Form 4 filing.