Costco's sales growth was weak in the fourth quarter, but this segment was strong.Investors are very forgiving when it comes to the stock of Costco Wholesale (COST 0.85%). Although it dipped last week after reporting a mere 1% year-over-year increase in revenue, it's still up 34% year to date, strongly outpacing the S&P 500.Costco has built up its reputation over many decades to become so deserving of that ironclad investor confidence. It's reliable for steady growth, and the market isn't willing to send it ...