24/7 Wall St.

In what could only be described as a roller-coaster week on Wall Street, one thing that was somewhat of a surprise given the volatility is that insiders stepped up to the plate and were buying shares in a big way. So much so that by our estimates insider buying volume swamped the sellers by a large margin. Given the lofty level of the markets, and the length of the bull market, that is clearly a positive.

We cover insider buying each week at 24/7 Wall St., and we like to remind readers that while insider buying is usually a very positive sign, it is not in of itself a reason to run out and buy a stock. Sometimes insiders and 10% owners have stock purchase plans set up at intervals to add to their holdings. That aside, it still remains an overall positive indicator.

Here are some companies that reported notable insider buying last week.

Phillips 66 (NYSE: PSX) had a big-time buyer on the desk once again this past week, and just like in all of 2016 the share count is huge. Warren Buffett’s Berkshire Hathaway, which is now a 10% owner of the company, was busy buying an additional 1,019,974 shares at prices that ranged from $77.08 to $77.39 piece. The total for the trade came to gigantic $79 million. Phillips 66 operates as an energy manufacturing and logistics company. Its stock closed the day on Friday at $79.09, so the timing looks good.

Seattle Genetics Inc. (NASDAQ: SGEN) had one of the biggest bio-pharmaceutical funds buying even more shares of the stock this past week. The Baker Brothers, a 10% owner of the company, bought a total of 447,311 shares at prices between $50.42 and $51.14. The total for that buy was $23 million. The fund may have been topping off the tanks as it has bought a gigantic amount of stock over the spring. Seattle Genetics is a biotechnology company that develops and commercializes antibody-based therapies for the treatment of cancer. Its stock closed Friday at $53.65, so the timing looks outstanding.

Penske Automotive Group Inc. (NYSE: PAG) saw the top insider at the company buying shares yet again last week. The CEO, the legendary Roger Penske himself, who is also a 10% owner of the company, bought a whopping 327,602 shares at prices that ranged from $47.62 to $48.49. That cost him a large $16 million. The transportation services company operates retail automotive and commercial vehicle dealerships principally in the United States and Western Europe, as well as distributes commercial vehicles, diesel engines, gas engines, power systems and related parts and services primarily in Australia and New Zealand. The stock closed last Friday at $49.11.

Wisdom Tree Investments Inc.‘s (NASDAQ: WETF) founder, who is also the CEO, bought shares this past week. Jonathan Steinberg, the son of famous Wall Street financier Saul Steinberg and husband of CNBC’s Maria Bartiromo, bought 100,000 shares of the stock at $10.23 apiece. The purchase came in a just over $1 million. The company operates as an exchange-traded funds sponsor and asset manager. Its stock closed Friday at $10.81 per share.

Fifth Street Senior Floating Rate Corp. (NASDAQ: FSFR) had a 10% owner buying a big pile of shares last week. Leonard M. Tannenbaum acquired a whopping 865,868 shares at a posted price of $8.52 apiece. The total for the trade was $7 million. The company is essentially a publicly traded hedge fund. It earns fees of for its services, but instead of stocks its specialty is managing the assets of business development companies. The shares closed last Friday at $8.51.

These companies also reported insider buying last week: Adamas Pharmaceuticals Inc. (NASDAQ: ADMS), Hersha Hospitality Trust (NYSE: HT), La Jolla Pharmaceutical Co. (NASDAQ: LJPC), PBF Energy Inc. (NYSE: PBF) and Sprouts Farmers Market Inc. (NASDAQ: SFM).

Despite the wild ride the markets have taken, the faith of insiders certainly has not been shaken. It is indeed a positive to see executives and 10% holders buying shares at current levels. It will be interesting to see if it holds with third quarter earnings right around the corner.