Billionaire Stanley Druckenmiller's Top Holding Is Up 37% This Year. Is the Market Pricing in the Full Story?

During his three decades as manager of the hedge fund Duquesne Capital, Stanley Druckenmiller averaged annual returns of around 30%, beating not just the S&P 500 but also many other major hedge funds. Druckenmiller wound down his fund in 2010, converting it into a family office.This left him still highly active in the investing game, but just with his own money.

Investors can keep track of the Duquesne Family Office's positions by looking up its latest 13F filings with the Securities and Exchange Commission (SEC). Per the latest filing, submitted Aug. 14, for the quarter ended June 30, 2026, Duquesne's largest position is in Natera (NASDAQ: NTRA). This position, worth around $865 million, makes up 16.6% of Duquesne's overall portfolio. While the family office has continued to build up a stake in the diagnostics company, much of its value is the result of the stock's big run-up thus far in 2026.

The question now is whether more upside remains for shares, or if the stock, after its strong extended run, is at risk of an extended pullback.

Stanley Druckenmiller. Image source: Getty Images.

Natera and its recent hot run

Since the start of the year, Natera has rallied by over 37%. For comparison, the S&P 500 is up just a relatively smaller 13.9% over this same time frame. Cutting-edge healthcare stocks can make volatile moves, in either direction, and that's what has happened with Natera, following a spate of positive news.

Earlier in the year, Natera shares traded sideways, even as investors remained appreciative of the company's unique strengths. This includes its dominant share of the minimal residual disease (MRD) testing market, a key segment given the strong demand for products that help detect cancer recurrence. Still, despite such strengths, valuation worries became the greater concern.

However, following two key developments, valuation worries have moved to the back burner. First, in June, shares rallied on news that Natera had received regulatory approval in Japan for its Signatera product for colorectal cancer testing. Second, and more importantly, investors reacted very positively to Natera's latest quarterly results.

As insiders sell, should you keep following Druckenmiller's lead?

On Aug. 6, Natera released results for the 2026 second quarter. During this period, revenue increased 37.7% year over year, from $546.6 million to $752.8 million. The company also reported a more than 100-basis-point improvement in gross margins, as well as further progress in reaching profitability. Management also raised full-year revenue guidance, from $2.85 billion to $2.91 billion.

Alongside promising financials, Natera also keeps making progress in expanding the label for its products. After the aforementioned win in Japan, the company is now seeking regulatory approval for Signatera's use as a test for muscle-invasive bladder cancer.

With the company still unprofitable, and shares trading for 16 times sales, valuation remains sky-high among medical device stocks. Near-term profit-taking, or worse, investor disappointment over further near-term developments, could lead to another sharp pullback in shares. It also doesn't help that insiders continue to sell shares, showing little interest in increasing their own personal positions.

Still, it's likely not irrational exuberance that's leading Druckenmiller to keep buying. Long-term forecasts call for double-digit revenue growth to persist, with earnings turning positive by 2028. Wait for further weakness before buying, but the long-term bull case remains intact for now.

Thomas Niel has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Natera. The Motley Fool has a disclosure policy.