Retail investors loaded up on Apple last month as the stock plummeted to its lowest levels of the year and the company doubled its capital return program. So much so that the stock now has more ownership than ever in the history of TD Ameritrade, which tracks the largest pool of retail investors.

The general thinking on Wall Street has been that retail is the so-called dumb money and so one would think the stock garnered the most retail interest as it hit an all- time high of $705 last year. But that wasn't the case.

Computerized algorithms are quickly replacing single-stock analysts and investors, leading to big changes in the way the stock market will value companies and increasing the chance that software glitches or hack attacks will jeopardize market stability.

Technological forces—including high-frequency trading, an explosion in exchange-traded funds and the proliferation of free information via social media—are behind this seismic shift, according to Nicholas Colas of ConvergEx Group.

"The changes that started with high-frequency and algorithmic trading are just the first step to an entirely different process of determining stock prices," Colas wrote in a sweeping note to clients Monday. "Will an equity market running on algorithmic autopilot serve to tie the managers of capital (senior executives) to the ultimate owners (shareholders) as robustly as one dominated by flesh-and-blood money managers? It seems a stretch to think so."

In other words, we've come a long way from the days of the Buttonwood tree and Benjamin Graham.

The false Twitter alert from the Associated Press which sent the Dow Jones Industrial Average down more than 140 points caused brief panic on the trading floors around Wall Street.

"It was panic," said one trader from a major firm who wished not to be named. "One guy sold a ton of the SPYs at that moment and then had to cover for a big loss."

The two-day pullback in stocks this week put the S&P 500 below the record levels of 2007's housing bubble and tech bubble of 2000, raising concern about a dreaded "triple-top" in the market that could keep a lid on any gains for the foreseeable future.

The S&P 500 hit a high of 1,552 in March 2000. After a biting recession, interest rates slashed to the basement by the Fed and then the biggest boom in housing ever, it recovered to a high of 1,576 in October 2007. Rinse and repeat and we find the S&P 500 at 1,541 today.

To the delight of many technical analysts, it broke this triple top last week. Unfortunately, it traded above the old record for just four days before poor economic data and earnings results this week dragged it back down into this 13-year range.

The two-day crash in the price of gold is one of the most devastating asset sell-offs ever witnessed on Wall Street, right up there with the stock market crash of 1987. What makes it that much worse is no one is exactly sure why it happened.

And until investors get some answers, the selling may continue, they say.

With all the uncertainty out there about the Federal Reserve, fiscal policy, Europe and North Korea, one would think it's hard enough to give an equity forecast for the end of this year. But the gang at Goldman is taking a stab at predicting market returns until 2016.

The global equity team at the elite Wall Street firm sees 9 percent annual total returns for the S&P 500 ahead, pushing the index up 20 percent to 1900 by the end of 2015. They see even bigger returns for Japan, Europe and the rest of Asia.

Gains will be "driven by strong earnings growth supplemented by a good dividend yield and some expansion in multiples," states the strategy paper. The forecasts rely "upon our economists' scenario for future economic activity and the tools for modeling earnings and discount rates that have so far been important inputs for setting our 12-month index targets." (Read More: You Must Understand This About Yield)

Insider selling at the biggest technology companies hit a record pace over the last six months even as investors snatched up shares, pushing the Nasdaq Composite Index to a 12-year high.

More than 55 million shares were sold versus 1,780 shares bought for a sell-buy ratio of an eye-popping 31,109 to 1 at the 10 biggest tech companies, including Microsoft, Oracle and Qualcomm, according to Alan Newman, editor of the Crosscurrents newsletter and market analyst for 49 years.

"Insider activity confirms the rosy scenario indicated by prices is only an illusion," wrote Newman in his latest letter. "Insiders have no confidence in their own companies. While prices appear to be indicating an all clear, we remain in one of the most egregiously speculative phases ever seen."

As the S&P 500 surged to a record close last month, retail investors cashed in high fliers such as Dell and Hewlett-Packard and snapped up securities with hefty dividend yields like General Electric, Intel, and real estate investment trusts, according to an inside look into six million funded accounts at TD Ameritrade.

The actions suggest a mild-tempered, more sophisticated approach by retail investors, who are often derogatorily referred to as the "dumb money" and thought to blindly chase momentum after stocks post big gains.

Hedge funds, on average, returned just above 3 percent in the first quarter of 2013, a brutal return compared to buyers of an S&P 500 index fund, who enjoyed a 10 percent return on their money.

Vocal activist and founder of Third Point Partners Dan Loeb was the standout, as timely bets on Yahoo, Japan and liquid natural gas play Cheniere Energy drove the firm's Ultra Fund to a 13.3 percent return through the end of March.

This bull market that seemingly won't quit is headed toward a correction this quarter, many investors said, citing recent history, the lack of retail investor participation and the upcoming earnings season.

"The second quarter has proven to be the period when the market finally provides the correction that many investors had begun to anticipate during the latter stages of the first quarter," said Brian Belski, chief investment strategist at BMO Capital Market, in a quarter-end note. "It is an appropriate time for investors to become tactically more defensive within portfolios."