United States Oil Fund, LP (USO) is showing up on our radar after HRT Financial LP, a 10%+ owner of the fund, filed a Form 4 disclosing a fresh open-market purchase of 13,649 shares at $155.30 apiece on September 14, 2026. The trade was worth $2,119,689.70 and brought HRT’s direct holdings to 61,589 shares.
That single transaction, however, is only the latest entry in a much larger pattern. According to the filings we’ve tracked, HRT Financial made nine separate open-market purchases of USO shares between September 11 and September 14, 2026, spending a combined $16,608,540 over that four-day stretch. We classify this kind of repeated, same-direction buying activity from a single insider as a ‘cluster buy’ — a signal that tends to draw more attention than any one transaction in isolation.
What the Filing Shows
Each leg of the purchase sequence was funded with HRT’s own capital, meaning the firm was adding to its position at prevailing market prices rather than receiving shares through options, grants, or other compensation-related mechanisms. The September 14 purchase itself was executed at $155.30 per share, a price point that sits within the range investors have seen from USO, an exchange-traded product designed to track the daily price movements of West Texas Intermediate light, sweet crude oil.
HRT Financial’s status as a 10%+ owner means its trading activity is subject to the same Section 16 disclosure requirements as company officers and directors, giving the public visibility into a stake that is large enough to influence, or at least reflect close attention to, the fund’s supply-and-demand dynamics over the period in question.
Why Clustered Buying Gets Noticed
Academic research on insider trading has repeatedly found that clustered purchases — multiple buys from the same insider or group of insiders in a short window — carry more statistical signal than isolated transactions, and have in some studies been associated with subsequent outperformance relative to the broader market. That research describes historical patterns and does not predict what will happen with any specific security going forward, and this article is not suggesting any course of action for readers.
The nine-trade, $16.6 million buying sequence from HRT Financial LP is now part of the public record for USO, and it joins a small but growing list of concentrated insider purchases we’ll continue tracking as new Form 4 filings are submitted to the SEC.
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Source: original SEC Form 4 filing.