Nielsen Holdings NV (NYSE: NLSN) has agreed to acquire Arbitron Inc. (NYSE: ARB) for approximately $1.26 billion, or $48 per share in cash (26% premium to yesterday’s closing price). Major Nielsen shareholders include The Blackstone Group, THL Partners, The Carlyle Group, KKR and Hellman & Friedman. www.nielsen.com

American Railcar Industries Inc. (Nasaq: ARII) has offered to acquire rival railcar maker Greenbriar Cos. (NYSE: GBX) for approximately $543 million, or $20 per share (5.4% premium to yesterday’s closing price). Carl Icahn controls American Railcar, while last month he reported nearly a 10% stake in Greenbriar. www.americanrailcar.com

ConocoPhillips (NYSE: COP) has agreed to sell its Algerian business to Indonesia’s Pertamina for approximately $1.75 billion. www.conocophillips.com

Elliott Management has offered to acquire business software maker Compuware (Nasdaq: CPWR) for approximately $2.3 billion, or $11 per share. That represents around a 25% premium to where Compuware was trading last month before Elliott disclosed that it holds around an 8% stake in Compuware. www.compuware.com

Joh. A. Benckiser, a German holding company, has agreed to buy Brooklyn Center, Minn.–based Caribou Coffee Co. (Nasdaq: CBOU) for approximately $340 million, or $16 per share (30% premium to Friday’s closing price). www.caribou-coffee.com

Cinven is in talks to sell Italian aerospace company Avio SpA for at least $4 billion to General Electric (NYSE: GE), according to the NY Times. Cinven acquired a majority stake in Avio in 2006 from The Carlyle Group and Finmeccanica for $3.3 billion. www.cinven.com

Denham Capital has agreed to sell its stake in the GNPower Mariveles project, a 600-megawatt power generating plant currently undergoing commissioning in the Philippines’ Bataan province, to Ayala Corp. The deal is valued at $155 million. www.denhamcapital.com

First Reserve Corp. and Trilantic Capital Partners have sold the assets of TLP Energy, an Oklahoma City-based oil and gas producer focused on the Texas Panhandle and Oklahoma, to NFR Energy. The deal was valued at approximately $655 million. NFR is a Houston-based portfolio company of First Reserve Corp. and Nabors Industries Ltd. (NYSE: NBR). http://www.nfrenergy.com

Home Depot (NYSE: HD) has acquired BlackLocus, an Austin, Texas-based provider of data-driven price optimization solutions for retailers. No financial terms were disclosed. BlackLocus last year raised $2.5 million in VC funding from DFJ Mercury and Silverton Partners. www.blacklocus.com

Industrial Opportunity Partners has sold Center Manufacturing, a Byron Center, Mich.-based maker of complex wielded assemblies, to Mayville Engineering Co. No financial terms were disclosed. Quarton Partners managed the process. www.centermfg.com

Palladium Equity Partners has agreed to sell Wise Foods Inc., a Berwick, Penn.-based maker of snack brands like Wise and Cheese Doodles, to Mexico-based Arca Continental (BMC: AC) for an undisclosed amount. www.e-arca.com.mx

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