Merger and acquisition activity sparked a late afternoon rally to send the markets soaring with the Dow leaping 138 points to close at 15,254. Nasdaq rose 9 points to 3465.

On the upside

American Safety Insurance (NYSE: ASI) will be acquired by Fairfax Financial Holdings for a premium of approximately $306 million in cash.

Tesaro (Nasdaq: TSRO) partnered with the European Network of Gynecological Oncological Trial Groups to conduct a Phase 3 clinical trial for the ovarian cancer treatment niraparib. Tesaro also partnered with Breast International Group and the European Organization for Research and Treatment of Cancer for a Phase 3 trial of niraparib for the treatment of breast cancer.

Falconstor Software (Nasdaq: FALC) partnered with IBM (NYSE: IBM) to integrate the FalconStor Virtual Tape Library with reduplication software into IBM servers for midmarket clients.

On the downside

Zynga (Nasdaq: ZNGA) will eliminate 520 jobs, or 18% of its workers, in order to save between $70 million to $80 million per year.

Trading restrictions on 82% of SolarCity (Nasdaq: SCTY) will expire on June 10.

National Bank of Greece (NYSE: NBG) announced on Friday a tender offer to purchase up to 22.5 million American Depositary Shares.

In the broad market, declining issues edged out advancers by a margin of nearly 10 to 9 on the NYSE while advancers outpaced decliners by more than 7 to 5 on Nasdaq. The broader S&P 500 index gained 9 points to 1640.