The most notable insider purchases of the past week or so came from return buyers. Warren Buffett acquired more of his oil stock, and huge buying continues in an entertainment giant. And insiders took advantage of a sell-off in a struggling cosmetics company’s shares as well.

Furthermore, another biotech has come public, tempting both directors and beneficial owners to scoop up some shares. Let’s take a quick look at these transactions.

Is Insider Buying Important?

A well-known adage reminds us that corporate insiders and 10% owners really only buy shares of a company because they believe the stock price will rise and they want to profit from it. Thus, insider buying can be an encouraging signal for potential investors. This is all the more so during times of uncertainty in the markets, and even when markets are near all-time highs.

The earnings-reporting season is still underway, so many insiders are prohibited from buying or selling shares. Below are some of the more notable insider purchases that were reported in the past week, starting with the largest and most prominent.

Mach Natural Resources

• Buyer(s): a director
• Total shares: more than 1.5 million
• Price per share: $15.50
• Total cost: around $80.0 million

This transaction was part of a public offering of common units. Anadarko Basin-focused independent upstream oil and gas company Mach Natural Resources L.P. (NYSE: MNR) completed two acquisitions last fall, funded in part by a prior secondary offering.

The share price is more than 15% lower than a year ago, much of the retreat following the announcement of the prior offering. Shares were last seen above the purchase price above. The $24.20 consensus price target is higher than the 52-week high and indicates that analysts see about 53% upside in the next 52 weeks. All five analysts who cover the stock recommend buying shares.

Note that this same director also acquired nearly 900,000 shares in December.

TKO

• Buyer(s): 10% owner Silver Lake West HoldCo
• Total shares: almost 390,500
• Price per share: $166.63 to $178.08
• Total cost: over $68.1 million

After scooping up over $39 million worth of shares in the prior week, this buyer came back for more.

TKO Group Holdings Inc. (NYSE: TKO) is the parent of Ultimate Fighting Championship and World Wrestling Entertainment. There has been speculation that UFC programming could end up on Netflix, and UFC recently named its official wireless provider in the United States. The fourth-quarter report is due soon.

Since the third-quarter report, the stock is up more than 49% and trading near an all-time high of about $179 per share. The $162.00 consensus price target suggests no upside in the next 12 months, yet all but four out of 18 analysts recommend buying shares, three of them with Strong Buy ratings

Note that the buyer’s stake is up to almost 2.6 million shares.

Occidental Petroleum

• Buyer(s): 10% owner Berkshire Hathaway
• Total shares: around 763,000
• Price per share: $46.64 to $47.00
• Total cost: more than $35.7 million

After scooping up more than $408 million worth of shares last summer, Buffett returned to further bolster the Occidental Petroleum Corp. (NYSE: OXY) stake to almost 265 million shares, or about 28%

The Houston-based company crushed third-quarter expectations, but both the top and bottom line are expected to decline in the upcoming report. Yet the shares are down more than 21% from a year ago, though they were last seen trading above just Buffett’s latest purchase price range. They recently hit a 52-week low of $45.17. Analysts now anticipate over 29% upside potential in the next 12 months to their consensus price target. Analysts on average have a Hold rating on the stock.

Sionna Therapeutics

• Buyer(s): two beneficial owners and two directors
• Total shares: more than 2.8 million
• Price per share: $18.00
• Total cost: almost $51.5 million

This clinical-stage biopharmaceutical company just had an initial public offering, and these buyers helped themselves to some of those Sionna Therapeutics Inc. (NASDAQ: SION) shares. This was the fourth biotech IPO of 2025, and the company raised around $219 million in its IPO, intended to advance its cystic fibrosis treatments. That is a market dominated Vertex Pharmaceuticals Inc. (NASDAQ: VRTX).

Since Sionna went public, its shares have changed hands for between $19.26 and $25.19 apiece, well above the IPO price. That is good news for the 10% owners who showed confidence in the company’s prospects by scooping up shares.

Estee Lauder

• Buyer(s): a director and an officer
• Total shares: 133,200
• Price per share: $64.13 to $69.01
• Total cost: more than $8.7 million

These two insiders picked up Estee Lauder Companies Inc. (NYSE: EL) shares after a sell-off in the wake of a disappointing earnings report, announced layoffs, and a further management change. The struggling company also slashed its dividend last fall.

The cosmetics giant’s stock is down about 7% but was last seen changing hands for more than the purchase price range above. Few of the 31 analysts who cover the stock recommend buying shares. However, their consensus price target of $76.48 suggests more than 12% upside in the coming 12 months. Note though that it may be skewed by an unusually high $120 price objective from one of those analysts.

And Other Insider Buying

In the past week, some insider buying was reported at Advanced Micro Devices, Amcor, Ares Capital, Becton Dickinson, Boston Scientific, Dow, Helmerich & Payne, Hillenbrand, Meritage Homes, 1-800-Flowers.Com, Reynolds Consumer Products, SLM, Synaptics, and Terex as well.

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