"What goes up must come down."

"All streaks must come to an end."

These two common phrases have held up pretty well over time, and on Tuesday the S&P 500 Index (SNPINDEX:^GSPC) fell victim to their applicability. While sunrises and sunsets have continued each day with remarkable discipline and consistency, an impressive streak for stocks operates on a much smaller timespan. Markets had doubtlessly been impressed with the index's eight day streak of gains, the longest such streak since January, but another day in the green wasn't in the cards for Wall Street Tuesday. Slipping on uncertain monetary policy and weak corporate earnings, the S&P lost 6 points, or 0.4%, to end at 1,676. Following are its three worst-performing components on a down day.

Marathon Petroleum (NYSE:MPC) took the biggest hit, losing 4.3% as oil refiners got hammered today. Marathon's fall today, however, wasn't merely dealt a bum hand by virtue of its industry's weakness; today's slip was company-specific. While Marathon doesn't report quarterly earnings until Aug. 1, it decided to give shareholders a heads-up that things weren't going to be rosy. The company is looking for income between $570 million and $600 million, compared to $814 million profits in the year-ago period, as margins were pressured.

Mosaic (NYSE:MOS) reported earnings today and promptly fell 3.6% after the announcement. The agricultural chemicals company suffered from lower prices of phosphate and potash, in addition to headwinds in global markets as a trio of factors combined to impact the quarter. On top of lower prices, a weakening Indian currency and a recently expired contract with a major Chinese buyer teamed up to hit results.

Lastly, wireless provider Sprint Nextel (NYSE:S) slumped 3.6% Tuesday. In a compelling embodiment of the notion that all streaks must one day come to an end, the stock finally pulled back after a four-day rise that saw shares rocket nearly 22% higher. The gains came on the back of Sprint's finalized acquisition by Japan's SoftBank, as well as a telecom sector that continues to consolidate power into just a few major players.

Fool contributor John Divine has no position in any stocks mentioned. You can follow him on Twitter, @divinebizkid, and on Motley Fool CAPS, @TMFDivine.

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