The short-seller added he also bought some call options for insurance in case he is incorrect on his bearish view.
Nvidia will report fiscal second-quarter results after the market close.
Nvidia did not immediately respond to a request for comment.
The company is one of the best performing stocks in the market. Its shares are up more than 50 percent year to date versus the S&P 500's 9 percent return.
Regular investors are rolling the dice on the common stock of Fannie Mae and Freddie Mac in a big way, making a risky bet that Congress and the Obama administration won't get their way in doing away with the government-controlled entities. A move that would leave the shares worthless.
The pair of mortgage finance companies, which now trade over the counter after their delisting from the NYSE, were among the most actively traded shares by the retail investor in June, according to TD Ameritrade's analysis of its 6 million funded accounts. They are right up there in popularity with the high-flying momentum stock Tesla.
This raises many questions. Does the retail investor know exactly what they are betting on? Do they know that these are not the preferred shares that pay a dividend and are owned by many hedge funds? Do they know that these shares are last in line in the capital structure and therefore last to get paid?
"I don't think the retail trader knows what they're doing," said Stephen Weiss of Short Hills Capital Partners. "They are looking to buy a lotto ticket and not realizing they could lose 100 percent of their capital in these things."
One of the rare bipartisan views shared by many lawmakers are that these enablers of the housing crisis five years ago should be totally nationalized. This is essentially what would happen under the bipartisan bill proposed by Sens. Bob Corker and Mark Warner that would wind down Fannie and Freddie, send most—if not all—their profits into U.S. coffers, and replace them with a government-run reinsurer.
(Read More: Hedge Funds vs. Treasury on Fannie Mae)
The American Dream used to be a house to call your own that you paid for with a steady paycheck after an honest day's work. But in this post-financial-crisis nation, the dream for many now means having a part-time job and being able to rent an apartment.
And with unemployment and wages stagnant, as well as uncertainty about the costs of the new health care act for employers, the pared-down expectations may be a trend for years to come.
"The quality of the jobs being added are quite low, especially relative to the jobs that were lost," said an economist from a major Wall Street investment bank, who declined to be named because he hasn't published on this trend yet. "Homeownership, especially for the younger, is quite low, showing perhaps some secular decline."
The jobs report on Friday showed that May unemployment was unchanged at 7.6 percent.
(Read More: How Home Ownership Causes Unemployment)
But digging deeper into the data reveals a different story. The unemployment rate was just 3.8 percent for those with a bachelor's degree and higher. Its 7.4 percent for those with only a high school degree.
The number of workers who are "part-time for economic reasons" is higher than it has ever been after every recession since 1950, according to the Department of Labor.
And average weekly hours for private employees remains 33.6 hours—about what it was just after the recession ended in 2009.
We shouldn't expect those average hours to rise, because small businesses and retailers face new health-care rules to be enacted in 2014. In fact, hours may even decline.
(Read More: Rising Rates Hit REITs Hard)
Investors reduced their overall equity exposure in May for the second month in a row even as the S&P 500 hit a record high, according to a monthly proprietary trading survey from TD Ameritrade.
The firm's so-called IMX Index, which monitors the behavior of the largest pool of retail traders, fell for a second month in value but still remains in the moderately high range.
"There's overall skepticism with the market at highs," said Nicole Sherrod, managing director of TD Ameritrade's Trader Group. "They were still taking profits and seeking yield."
One interesting tidbit after peeking inside their customers' books was the explosion of trading in Tesla, which was the most actively traded stock in their retail pool.
The electronic-car maker nearly doubled in May as short-sellers were forced to cover after stellar reviews for the company's flagship vehicle, the Model S. Founder Elon Musk said at its annual meeting that he will sell 15,000 units of the luxury sports car this year.
"Our traders tend to chase momentum," said Sherrod.
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)