In a July 13th post, I pointed out that Google Inc. (Nasdaq: GOOG) and Yahoo! Inc. (Nasdaq:YHOO) were the only two stocks we cover that have risen since we opened for business at the beginning of May. The market's reaction to Yahoo's earnings demonstrates what a treacherous investing environment we face.

Although these two stocks were up, I was not comfortable investing in them. As I noted last week, "In the current investing climate, I would hesitate to commit funds even to Google and Yahoo because a slight stumble in earnings results or guidance could slam these stocks."

As Sarah Gilbert pointed out, that is exactly what happened this evening. Specifically, Yahoo delayed the launch of a much-anticipated upgrade of its search advertising system and issued a 2006 revenue outlook below Wall Street forecasts, sending its shares down 13%.

Based on after-hours results, all the stocks we cover -- Apple Computer, Inc. (Nasdaq: AAPL), eBay, Inc. (Nasdaq: EBAY), General Electric (NYSE: GE), Google, Microsoft Corporation (Nasdaq: MSFT), Time Warner Inc. (NYSE: TWX), Wal-Mart Stores, Inc. (NYSE: WMT), and Yahoo -- are now down 11% from where they were at the beginning of May, compared to a 5% decline in the S&P 500.

This is a nasty blow from just a week ago when Google and Yahoo had been up since the beginning of May by 5% and 4% respectively and the overall group of eight stocks was down 6%.

From best to worst, here is how our eight stocks have fared using after-hours prices as of July 19th 18th:

• Google -2%
• GE -5%
• Wal-Mart -6%
• Microsoft -7%
• Time Warner -8%
• Yahoo -13%
• Apple -24%
• EBay -25%

The Yahoo decline is typical of a market which is always poised to slam a company's stock for any deviation from increasingly high expectations.

So although it may be annoying, I feel a need to pound the table for money market funds. Their yields will drop when the Fed starts cutting rates. But that won't happen until inflation is under control. In the meantime, money market fund yields are likely to rise with far less risk to investors than these eight stocks.

I am neither long nor short shares of Apple, eBay, Google, Microsoft, Time Warner, Wal-Mart, or Yahoo. I own shares of GE. For more about me, click here.