The top after-market NYSE gainers Friday were MasTec, Oasis Petroleum, Matador Resources, Janus Capital Group and Putnam Municipal Opportunities Trust. The top after-market NYSE losers were Imperva, Ocwen Financial Corp, Radioshack Corp, Game Stop Corp and Permian Basin Royalty Trust.

Gainers

MasTec, Inc. (MTZ) shares surged 2.10 percent to $18.45 in post-market trading. The stock has a 52-week low of $12.86, a 52-week high of $22.72 and $1.37 billion in market capitalization.

Oasis Petroleum Inc. (OAS) shares advanced 2.01 percent to $30.40 in post-market trading after surging 3.62 percent in regular trading.

Matador Resources Co. (MTDR) shares advanced 1.52 percent to $10.36 in post-market trading.

Janus Capital Group Inc. (JNS) shares gained 1.52 percent in post-market trading. The company stock climbed more than 10 percent in regular trading after announcing that it has entered into a strategic alliance with the Dai-ichi Life Insurance Company. As part of this alliance, Dai-ichi Life will support JNS's distribution initiatives in Japan and plans to invest $2 billion of its general account assets with JNS, including seed capital for Janus Capital investment strategies.

Putnam Municipal Opportunities Trust (PMO) shares rose 1.28 percent to $13.40 in post-market trading.

Losers

Imperva Inc. (IMPV) shares plunged 5.01 percent to $31.42 in post-market trading. The company stock climbed more than 26 percent in regular trading after announcing second quarter earnings. Its second quarter net loss narrowed to $0.02 per share from $0.16 per share in the same period last year.

Ocwen Financial Corp. (OCN) shares plunged 3.75 percent to $22.59 in post-marketing trading. The stock has a 52-week low of $11.72, a 52-week high of $23.58 and $3.17 billion in market capitalization.

Radioshack Corp. (RSH) shares fell 2.03 percent to $2.96 in post-market trading.

Game Stop Corp. (GME) shares declined 1.80 percent to $17.42 in the post-market session. The company stock surged more than 5 percent in regular trading.

Permian Basin Royalty Trust (PBT) shares fell 1.77 percent to $18.30 in post-market trading. The stock has a 52-week low of $16.49, a 52-week high of $23.25 and $868.32 million in market capitalization.