When insiders sell shares, it indicates their concern in the company's prospects or that they view the stock as being overpriced. Either way, this signals an opportunity to go short on the stock. Insider sales should not be taken as the only indicator for making an investment or trading decision. At best, it can lend conviction to a selling decision.

Below is a look at a few recent notable insider sales.

Alphabet

• The Trade: $Alphabet-C(GOOG.US)$ Director Sergey Brin disposed a total of 12263 shares at an average price of $2,796.23. The insider received $34,290,145.64 as a result of the transaction.

• What's Happening: The company's stock gained around 5% over the past six months.

• What Alphabet Does: Alphabet is a holding company, with Google, the Internet media giant, as a wholly-owned subsidiary.

Morningstar

• The Trade: $Morningstar(MORN.US)$ Executive Chairman Joseph Mansueto sold a total of 47030 shares at an average price of $307.36. The insider received $14,455,179.50 from selling those shares.

• What's Happening: Morningstar, last month, announced plans to acquire wealth management platform provider Praemium's UK and International Business for £35 million.

• What Morningstar Does: Morningstar is a provider of independent investment research to financial advisers, asset managers, and investors. The company focuses its operations on two core sectors: data and research.

Aptiv

• The Trade: $Aptiv PLC(APTV.US)$ President and CEO Kevin P Clark sold a total of 11660 shares at an average price of $159.65. The insider received $1,861,544.62 as a result of the transaction.

• What's Happening: Aptiv recently agreed to acquire wind River from TPG Capital for $4.3 billion in cash. Wind River's software enables the secure development, deployment, operations, and servicing of mission-critical intelligent systems.

• What Aptiv Does: Aptiv's signal and power solutions segment supplies components and systems that make up a vehicle's electrical system backbone, including wiring assemblies and harnesses, connectors, electrical centers, and hybrid electrical systems.

Dropbox

• The Trade: $Dropbox(DBX.US)$ Chief Legal Officer Bart Volkmer sold a total of 11000 shares at an average price of $24.26. The insider received $266,833.60 from selling those shares.

• What's Happening: The company's stock gained around 6% over the previous year.

• What Dropbox Does: Dropbox is a leading provider of cloud storage and content collaboration tools with an emphasis on individuals and SMB.

Micron Technology

• The Trade: $Micron Technology(MU.US)$ SVP, Worldwide Sales Michael Bokan sold a total of 20000 shares at an average price of $93.83. The insider received $1,876,600.00 from selling those shares.

• What's Happening: Micron recently said it has begun volume shipments of the world's first 176-layer QLC NAND SSD.

• What Micron Does: Micron historically focused on designing and manufacturing DRAM for PCs and servers. The firm then expanded into the NAND flash memory market.