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Stocks with high share prices like Amazon and Alphabet are vulnerable to market manipulation

  • High share prices lead to very thin order books.
  • Thinly traded stocks are more vulnerable to market manipulation.

With Amazon and Alphabet shares hovering around $1000, there's been plenty of debate about whether the stocks should be split, at least for the benefit of retail investors who may want to buy at lower prices.

However, there's another important factor to consider: High stock prices could leave the door open for potential market manipulation.

That's according to Michael Friedman, General Counsel at electronic trading firm Trillium. Friedman is a securities lawyer and a software designer who wrote a software program to detect manipulation.

According to Friedman's logic, it simply comes down to size. When share prices are very high, order books are very thin. That means there are very few bids and very few offers waiting to be executed in the market. Any single trade can bump the price around.

More bumps mean more chances for manipulation. Examples include layering and spoofing, where artificial orders are submitted but canceled right before execution. These are ways of shifting where the market price heads.

Many other experts have also pointed out that thinly traded stocks are ripe for such problems. It's about the number of shares traded, regardless of market cap.

Friedman told CNBC that exchanges operate best when stocks are between $20 and $80, optimizing the order book and efficiency across other trading platforms. Because stock prices can only move 1 penny at a time, Friedman says the ideal stock price is one that allows for a reasonable number of shares to trade at each penny level.

Over 150 stocks in the S&P 500 Index closed Friday with share prices above $100. Including 15 stocks above $300.