NEW YORK (TheStreet) -- Twitter (TWTR) - Get Report fell after a high-level executive announced his resignation, a move that comes within weeks of another announcement the CEO would be leaving. Micron Technology (MU) - Get Report tanked after an analyst cut its price target. Facebook (FB) - Get Report slipped after announcing its opened its first office in Africa.

Twitter fell 3% to close at $34.21.

The social networking company edged lower after Rishi Garg, Twitter's vice president of corporate development and strategy, announced his resignation in a tweet roughly 15 minutes before the markets closed Friday. In his announcement, Garg said simply, "After an amazing ride as Twitter's VP Corporate Development and Strategy, I'm saying farewell today."

Garg, who joined Twitter a little over a year ago, is leaving to pursue other projects, according to a Re/code report. Twitter's chief financial officer, Anthony Noto, responded to Garg's tweet by wishing him well and saying to count him in for a seed funding round.

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Twitter's former VP Garg oversaw the company's acquisitions of Periscope, a live streaming video business, and also advertising company Niche, according to a report in Fortune. The move also comes two weeks after Twitter announced CEO Dick Costolo would be stepping down.

Micron Technology tanked 4.7% to end the session at $18.73.

The semiconductor maker fell after Bernstein analyst Mark Newman cut Micron's price target to $28 a share from $45 a share, according to a report in Benzinga.

Newman, according to Benzina, stated, "Micron's DRAM cost guidance of up low single digits confirms our worst nightmares on their problematic 20nm DRAM shrink. DRAM margins will fall substantially in FQ4'14 and the stock is dead money until the company can prove that the shrinks are back on track."

He further noted that the issues surrounding Micron's 20nm DRAM shrink is expected to hit Micron, in particular, rather than the wider chip market.

Facebook slipped 2.5% to finish the regular session at $85.80.

The social network giant edged down after announcing it had opened its first office in Africa. The move into Johannesburg, South Africa, is designed to assist businesses in connecting with people, both locally and throughout the region. Currently, Facebook has 120 million users in Africa, up from 100 million in September last year. And the vast majority of its users in Africa, 80%, access Facebook through their mobile phones.

Facebook is receiving strong advertiser partnerships and adoption of its products across all regions of the world, including Africa, Nicola Mendelsohn, vice president of Europe, Middle East and Africa for Facebook, said in a statement. "In first quarter 2015, 52% of our total ad revenue came from outside the US and Canada. But we're just getting started," said Mendelsohn.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.