(For more market insights, including options activity, click on ; for the Day Ahead newsletter link.reuters.com/mex49s; for the Morning News Call newsletter, link.reuters.com/nex49s) U.S. stocks fell on Monday on concern China's economy is continuing to lose momentum and the confrontation between Ukraine and pro-Russia separatists escalated. The Dow Jones industrial average was down 0.47 percent at 16,435.73, the S&P 500 down 0.3 percent at 1,875.59 and the Nasdaq Composite down 0.18 percent at 4,116.362.
** HYPERDYNAMICS CORP, $2.55, +71.14 pct
The oil and gas company said its project partner Tullow Oil had lifted the force majeure declared on its offshore exploration block in Guinea.
Hyperdynamics said it was trying to satisfy the conditions necessary to resume production, including a clarification that a U.S. regulatory investigation of the company would not hurt Tullow's operations under the production sharing contract.
** CADIZ INC, $7.899, +27.82 pct
The Orange County superior court on Friday upheld the validity of the environmental approvals for a water conservation, recovery and storage project by the land and water resources developer. The trial court denied all six petitions challenging the project's environmental review.
** BROADSOFT INC, $20, -20.00 pct
The company, which provides internet-based communications services to telecom companies, forecast second-quarter profit and revenue below analysts' estimates. It also reported lower-than-expected first-quarter results on Monday.
** B/E AEROSPACE, $99.04, +11.33 pct
The company, a $9 billion maker of aircraft cabin interior products, said on Sunday it was exploring strategic alternatives including a possible sale, merger or spin off of the company or selected businesses.
German aircraft seating maker Recaro is looking into the news, an executive said on Monday.
** AROTECH CORP, $3.87, +14.84 pct
The defense and security products company said its battery and power systems business had received new orders from military customers for about $5.2 million.
** TWITTER INC, $39.03, +0.03 pct
The six-month "lockup" - the period after the initial public offering during which early investors are barred from selling their shares - ends on Monday. Restrictions on about 470 million shares will be removed. The expiration of the lockup period could put additional pressure on the stock.
According to an article in the May 5 edition of Barron's, Twitter still looks overpriced even after a 47 percent drop from its late December high of $74.
** TYSON FOODS INC, $39.35, -7.74 pct
The largest U.S. meat processor reported weaker-than-expected quarterly profit on higher expenses and said it expects pork supplies to be down as much as 4 percent this year due to a deadly piglet virus.
** PFIZER INC, $30.05, -2.28 pct
The company reported revenue well below Wall Street expectations on falling sales of generic medicines, underscoring its interest in pursuing a $106 billion bid for rival AstraZeneca to promote new business growth.
** JPMORGAN CHASE & CO, $54.67, -1.64 pct
The investment bank expects second-quarter revenue from bond and equity trading to decline by about 20 percent from a year earlier, the biggest U.S. bank by assets said on Friday.
Citigroup and Morgan Stanley cut their price target on the company's stock.
** NORDION INC, $12.32, +6.39 pct
Sterigenics, a sterilization services provider owned by private equity firm GTCR LLC, raised its buyout offer for Nordion to $758 million from $727 million on Monday, after the Canadian medical isotope supplier received a rival bid from an unnamed buyer.
** AAON INC, $31.67, +9.58 pct
The maker of air-conditioning and heating equipment reported a 37.6 percent rise in first-quarter profit due to higher prices. The company also announced a 30 percent increase in its semi-annual cash dividend. [ID;nMKWfWgnSa]
** REALOGY HOLDINGS CORP, $37.06, -13.13 pct
The real estate services company said it expected second-quarter home sales to be down 5-7 percent at two its business - Real Estate Franchise Services, and Title and Settlement Services.
** TREX CO INC, $69.46, -12.53 pct
The maker of wood and plastic composite products reported first-quarter results that missed analysts' average estimates as a severe winter led to a decrease in sales.
** MATTSON TECHNOLOGY INC, $2.077, +11.67 pct
Chief Executive Chen Fusen Ernie has purchased 20,000 shares in the company at $1.93 for a total of $38,600. Mattson makes semiconductor wafer-processing equipment.
** AMBARELLA INC, $23.48, -5.09 pct
The video-processing chip maker's Chief Executive, Wang Feng-Ming, sold 20,500 shares in the company, according to a filing by Ambarella late on Friday.
Chief Technology Officer Kohn Leslie also sold 42,000 shares.
** TARGET CORP, $60.18, -2.95 pct
The company's Chief Executive and Chairman Gregg Steinhafel is leaving in the wake of the devastating data breach late last year that hurt profits, shook customer confidence in the No. 3 U.S. retailer and prompted congressional hearings.
** AUXILIUM PHARMACEUTICALS INC, $20.85, -2.93 pct
The company posted a bigger quarterly loss due to higher operating expenses and lower sales of its testosterone gel, Testim.
** ORBITZ WORLDWIDE INC, $7.18, -3.23 pct
The online travel agency on Monday reported higher-than-expected first quarter revenue and forecast revenue for the current period that topped current analysts estimates.
** GOLDMAN SACHS GROUP INC, $156.72, -1.36 pct
A major proxy advisory firm recommended shareholders vote against Goldman Sachs executive compensation plan and added that Morgan Stanley was also paying its top staff too much.
** ARIAD PHARMACEUTICALS INC, $7.595, +5.05 pct
Jefferies & Co analyst Eun Yang on Friday raised her rating on the company's stock to "buy" from "hold", saying that a survey of doctors showed that their use of the company's leukemia drug was minimally impacted by its temporary suspension from the market and its restriction to a smaller group of patients.
Sales of the drug, Iclusig, were suspended in October after it was associated with a higher-than-expected risk of life-threatening blood clots and narrowing of blood vessels, but Ariad resumed selling it with a revised label in January.
Yang also said Jefferies' 50-physician survey indicated that sales of Iclusig were steadily growing after its re-entry in the market, and raised her price target on the Ariad stock to $14 from $8.
** SINA CORP, $47.34, -1.68 pct
Chinese Internet firm Sina said it was fined 5.1 million yuan ($815,038) by Beijing authorities for allowing "unhealthy and indecent content" on its online reading channel and on its main website.
** KING DIGITAL ENTERTAINMENT PLC, $18.55, +5.64 pct
The three lead underwriters of the company's IPO started coverage of the stock with "buy" ratings or the equivalent, two days ahead of the release of the "Candy Crush Saga" game maker's first results as a public company.
** SOTHEBY'S, $44.44, +2.42 pct
Sotheby's said it reached an agreement with Daniel Loeb's Third Point LLC, giving the hedge fund three seats on the auctioneer's board.
** KBR INC, $24.51, -5.15 pct
The engineering and construction company said it intended to restate its financial statements for the year ended Dec. 31, 2013. The company also said it had identified an overstatement of about $9 million in pretax revenue for the quarter ended March 31, 2014.
** LA JOLLA PHARMACEUTICAL CO, $9.23, +2.10 pct
HC Wainwright & Co analyst Reni Benjamin started coverage on the company's stock with a "buy" rating and a target price of $17, saying that its lead experimental drug showed the best efficacy and safety in its class, when used as a treatment for chronic kidney disease.
Benjamin said that the company could attract partners for the drug, codenamed GCS-100, which inhibits a protein linked with inflammatory diseases, as interest in the fields of inflammation and fibrosis grows.
Noble Financial analyst Rahul Jasuja also raised his price target on the company's stock to $34 from $16. (Compiled by Natalie Grover; Edited by Maju Samuel)