The stock market's severe drop could be an ominous sign

Last week, it felt like the bottom dropped out of the stock market.

The blue-chip Dow Jones industrial average fell 4.5 percent for the week, ending with a 559-point rout Friday that left the index in negative territory for the year.

The benchmark Standard & Poor's 500-stock index has fallen into a "correction," meaning it's off more than 10 percent from its peak reached Sept. 20.

And once-highflying tech stocks faltered with Apple, Facebook and Google parent Alphabet all ending last week showing stock-price losses for the year - driving the Nasdaq composite index into a correction too.

So is this it - the end of the decade-long bull market? Or is it the sort of