24/7 Wall St.

What a week for equity investors as the S&P 500 and the Dow Jones Industrial Average raced to all-time highs. In what could be described as a near-perfect selling scenario, insiders at some of the highest profile companies on Wall Street took advantage of the breakout highs and liquidity and sold some gigantic chunks of stock. While it may raise an eyebrow, selling shares at what could be the top of the market is hardly unusual.

We cover insider selling every week at 24/7 Wall St., and we like to remind our readers that just because an individual or 10% institutional owner is selling stock, that is no cause for immediate alarm. Many top executives, and even directors, are compensated with stock and often sell just to diversify or purchase other assets.

Here are companies that reported notable insider selling last week.

Facebook

For the second week in a row, Facebook Inc. (NASDAQ: FB) is the insider selling leader as a director at the company, Jan Koum, sold two gigantic blocks of the social media giant’s shares. He sold a total of 1,721,436 shares at prices posted at between $118.16 and $117.98. The total for the sale came in at a humongous $203,353,086.

Koum, an internet entrepreneur and computer programmer, is the CEO and co-founder of WhatsApp, a mobile messaging application that was acquired by Facebook in February 2014 for $19 billion. Facebook shares closed Friday at $116.86 apiece, so the transactions seem well timed.

Shake Shack

This past week, a Shake Shack Inc. (NYSE: SHAK) director parted with some shares. That director and 10% owner sold a total of 300,000 shares of the company at prices that ranged from $35.51 to $37.09. The total for the sale came in at $11 million.

The company owns, operates and licenses Shake Shack restaurants that offer hamburgers, hot dogs, crispy chicken, crinkle-cut fries, shakes, frozen custard, beer, shakes, wine and other products. The stock closed Friday at $38.10, so the sale may have been a bit premature.

Costco

Two Costco Wholesale Corp (NASDAQ: CSCO) executive vice presidents, one current and one former, were selling shares this past week. Together they sold a total of 22,156 shares of the retail giant at prices that ranged from $165.54 to $166.88 per share. The total for the sale was posted at $4 million. Costco shares closed trading on Friday at $166.41.

Media General

A very well-known Media General Inc. (NYSE: MEG) investor sold some shares last week. John Muse, who was once the partner of Tom Hicks at Hicks-Muse, is a director at the company, and he parted with a total of 102,928 shares of the stock at prices between $17.578 and $17.87 apiece. The total for the sale was posted at $1,834,500.

Media General owns and operates television stations in the United States. The company operates through two segments, Broadcast and Digital, and it owns and operates 71 network-affiliated stations and their associated digital media and mobile platforms in 48 markets. The shares closed Friday at $17.77.

Western Gas Partners

Somebody from the Western Gas Partners L.P. (NYSE: WES) board also was selling stock last week. A director at the company shed a total of 36,915 shares at prices that ranged from $50.00 to $50.70. The total for the sale was posted at $2 million.

Western Gas Partners acquires, develops, owns and operates midstream energy assets in the Rocky Mountains, the Mid-Continent, north-central Pennsylvania and Texas. The company is involved in gathering, processing, compressing, treating and transporting natural gas, condensate, natural gas liquids and crude oil. Its shares closed Friday at $49.11, so another well-timed sale, it appears.

These companies also reported insider selling last week: Acuity Brands Inc. (NYSE: AVI), American Airlines Group Inc. (NYSE: AAL), Constellation Brands Inc. (NYSE: STZ), Q2 Holdings Inc. (NYSE: QTWO) and Ross Stores Inc. (NASDAQ: ROST).

With the market right at all-time highs, insider selling swamped buying yet again last week, and the imbalance should be no surprise. It should be noted that when the market took a big tumble to start 2016, insider buying was decidedly much higher than selling.