Why Intuitive Surgical, Diamond Offshore Drilling, and Transocean Ltd. Are Today's 3 Worst Stocks

It was tough to lose money in the stock market today. If you threw a dart at the stock universe today and invested in whatever company the dart landed on, you'd pick a winner seven in 10 times -- unless you missed the dartboard entirely and lodged your dart in an obscure bond, commodity, or innocent bystander, of course. I don't recommend this as an investment strategy, and if you're endangering passerby every time you play darts, you should probably stop doing that as well -- but I digress. Intuitive Surgical , Diamond Offshore Drilling , and Transocean Ltd. ended as some of the worst stocks in the S&P 500 Index today, despite the overall bullishness. The S&P added 20 points, or 1.1%, to end at 1,872 on Wednesday.

Intuitive Surgical lost 6.7% today after it gave investors a courtesy heads-up that first quarter revenue was going to be severely disappointing. The robotic medical devices company doesn't officially report first quarter results until April 22, but often when companies figure out their fiscal quarters will disappoint Wall Street, they let investors know beforehand. Sales of Intuitive Surgical's da Vinci robot plummeted in the first quarter, falling from $256 million a year ago to an estimated $106 million in the most recent period. Although shareholders took heavy losses today, the company's newest da Vinci model, the da Vinci Xi, was just approved by the FDA, which is great news and should offer a solid new revenue stream.

Diamond Offshore's "Rigamarole" magazine. Source: company website.

Shares of Diamond Offshore Drilling also ended toward the bottom of the index, shedding 4.2% Wednesday. Diamond Offshore was joined in the lowest depths of the S&P by fellow rig operator Transocean, which saw shares slump 2.7% today. Both stocks were downgraded just yesterday by investment bank Barclays, as the bank complained that "rate momentum" was trending lower. Simply put, both Diamond Offshore and Transocean are contract drillers, renting out their platforms to energy companies who want to excavate that precious black gold from the floor of the ocean.

My colleague Tyler Crowe beat Barclays to the punch when he expressed his concern about Diamond Offshore and Transocean specifically, worrying that their lack of investment in capital expenditures was depleting the utility of their fleets, losing each company market share, and driving down the value of their contracts.