The Dow Jones Industrial Average (DJINDICES:^DJI) fell more than 175 points to start the week as of 11:30 a.m. EST. Dow Jones component Microsoft (NASDAQ:MSFT) traded lower alongside its index, as did other tech stocks including Facebook (NASDAQ:FB). Yandex (NASDAQ:YNDX) was particularly hard-hit by the ongoing Ukrainian situation.

Russian troops arrive in the Crimea
The Dow Jones' sell-off appears to be prompted by ongoing tensions in Crimea, an autonomous republic within Ukraine. Russian troops entered Crimea late last week, prompting speculation of a forthcoming conflict. Markets around the globe have moved lower, as any military action could disrupt the global economy, particularly in the near term.

The Russian stock market has been particularly hard-hit, making the Dow Jones' sell-off look tame. Oil prices have risen sharply in the wake of the escalation, as Russia remains a major supplier of fossil fuels.

Microsoft shakes up management
Reports of an ongoing management shake-up may have been behind Microsoft's 1.8% drop. According to Re/code, Microsoft executive vice presidents Tony Bates and Tami Reller are leaving the company, and company insiders will be promoted to replace them. While a change in management could have some effect on operations, it's far from surprising, given that Microsoft just named a new CEO, and shouldn't be seen as fundamental to the company's future.

Facebook's COO could be on her way out
Like Microsoft, Facebook could be about to undergo a management change. The Daily Mail reported that COO Sheryl Sandberg, is considering running for a U.S. Senate seat. Business Insider, however, cited a source claiming that the report is completely untrue.

Sandberg is highly regarded, and her exit from the company could be seen as a negative. Nevertheless, speculation of political aspirations have hung around Sandberg for years, so if the report proves true, it wouldn't be all that surprisng.

Yandex shares slammed
Yandex was one of the worst-performing tech stocks on Monday, down more than 14% early in the session. Yandex is one of Russia's largest publicly traded tech firms, making it obviously susceptible to the ongoing moves in the nation's stock market. Yandex operates Russia's largest search engine, and its business is largely confined to Russia and neighboring countries, including Ukraine.

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