Benzinga's M&A Chatter for Tuesday March 4, 2014

The following are the M&A deals, rumors and chatter circulating on Wall Street for Tuesday March 4, 2014:

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AMCOL International

announced Tuesday that its Board has unanimously approved an amended merger agreement with Imerys

, under which which AMCOL shareholders will receive $45.25 per share in cash for each share of AMCOL common stock they own. Imerys had last offered $42.75 per share. The Board acknowledged recipt of Minerals Technologies

offer of $45.00 per share and determined it was not superior to the Imerys offer. The deal is expected to close in H1 2014. AMCOL International closed Tuesday at $46.28, a loss of $0.07.

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Shares of Riverbed Technology

moved lower Tuesday, following a press release from Elliott Management in response to Riverbed's announced increased share buyback. Elliott said Riverbed's buyback announcement is more "Clear evidence of the Board's entrenchment" Riverbed announced an additional $250 milllion buyback authorization on Tuesday, bringing the total to $750 million. The company has rejected offers of $19.00 and $21.00 per share from Elliott. Riverbed Technology closed Tuesday at $21.33, a loss of 2%.

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Facebook is said to be in talks to acquire solar-powered drone company Titan Aerospace, according to

. The purchase price is said to be $60M. Facebook declined comment on the report, while a spokesperson for Titan Aerospace cold not be reached for comment. Facebook closed Tuesday at $68.80, a gain of 2%.