Losing money is always painful. But on days like today, when the Dow Jones Industrial Average hits an all-time high, European equities reach a 4 1/2-year high, and the S&P 500 Index ends merely 25 points from setting a record of its own, losing money is downright brutal.

Not only did J.C. Penney Company, Inc. (NYSE:JCP) appear on this list yesterday, but today we see it return for the No. 1 Worst Stock spot, while yesterday it was merely No. 2. All this after I cautioned the companies on yesterday's list to learn from their poor performances. Tsk, tsk. Some never learn. Not content with 5.4% losses Monday, on Tuesday shares cratered 10.6% further. The nosedive continues after Monday's news that J.C. Penney's third-largest investor is looking to sell a massive block of 10 million shares.

Intuitive Surgical, Inc. (NASDAQ:ISRG) stumbled 2.8% today as reports surfaced about lawsuits resulting from botched surgeries involving the company's revolutionary robots. The stock is likely to remain volatile while safety and legal concerns swirl around the company. Last Thursday, the stock dropped 11%, only to rally more than 8% Friday as fears about a potential FDA investigation came to light and then subsided. One legitimate question to consider before fleeing from the stock: How many of these problems are issues with the machines, as opposed to the way the machines were used?