U.S. stock prices dropped sharply today in response to disappointing earnings announcements from Caterpillar (CAT), Sonoco (SON) and Google (GOOG).

Caterpillar, the world's largest maker of earthmoving machines, reported that its second-quarter profit fell 21 percent as a result of falling demand for truck engines and the weak U.S. housing market. Although the company expects full-year revenues to decline approximately 12 percent this year, it expects sales from abroad to climb 24 percent.

Meanwhile, Sonoco Products – the world's largest maker of composite cans – announced that its profits fell 14 percent due to lower demand for consumer packaging products and paper tubes; profits were also affected by costs incurred by the company to clean up a Wisconsin river.

As of 12:30 this afternoon, Google's (GOOG) stock had declined 5.7 percent, after reporting yesterday evening that its second-quarter earnings fell 8 percent from the previous quarter research expenses soared 88 percent.

Boston Scientific Corp. (BSX), the world's second-largest maker of heart devices, also reported disappointing earnings, as sales of the company's top-selling drug-coated stents fell 32 percent.

In an article I wrote last month, "Sliding Profits to Trigger Falling Stocks," I warned our readers about slowing corporate profit growth. On Tuesday of this week in my article "Up, Up and Away!," I mentioned that the latest corporate earnings estimates from Standard & Poor's suggested U.S. equity prices may soon fall.

Earlier in the week, I alluded our readers to the fact that fewer and fewer stocks have been participating in the market's advances, and I informed our readers that whenever advances in the major market indices are not accompanied by broad participation, stock prices. So, today's big sell-off should come to no surprise to astute investors.

Looking forward, I expect U.S. stock prices to continue to pull back over the coming week.