Ocwen, Gilead Sciences, Caesar's, Blackberry, and Achillion are big market movers

Stocks that moved substantially or traded heavily Monday on the New York Stock Exchange and the Nasdaq Stock Market:

NYSE

Ocwen Financial Corp., down $5.89 to $16.01

The subprime mortgage servicer's executive chairman will resign in a settlement that also provides $150 million to homeowners.

Nabors Industries Ltd., down 53 cents to $13.10

The oil drilling services company's stock fell as the price of oil continued its monthslong decline on prolonged weak demand.

Nasdaq

Enanta Pharmaceuticals Inc., up $4.70 to $51.32

The biotechnology company's development partner AbbVie Inc. received FDA approval for the Viekira Pak hepatitis C treatment.

Gilead Sciences Inc., down $15.55 to $92.90

Viekira Pak, a competitor to Gilead's hepatitis C treatments Sovaldi and Harvoni, was named the preferred treatment by the nation's largest pharmacy benefits manager.

Achillion Pharmaceuticals Inc., up $1.28 to $15.49

The biotechnology company reported positive results from two studies focusing on a treatment regimen for hepatitis C patients.

Caesar's Entertainment Corp., up $1.51 to $15

The casino operator will buy an affiliate in an all-stock deal, giving shareholders a 62 percent stake in the combined company.

Blackberry Ltd., up 69 cents to $10.68

The company is working with Boeing Co. to develop a smartphone with high-tech security features aimed at government agencies.

Taser International Inc., up $2.08 to $26.06

The stun gun and body camera maker reported nearly 1,900 orders received and expected to ship during the fourth quarter.