Wikipedia
"If-Then-Else" is the eleventh episode of the fourth season of the Person of Interest television series. It originally aired on January 6, 2015, on CBS. It is the seventy-ninth overall episode for the series.
"If-Then-Else" was written by Denise Thé and directed by Chris Fisher. The episode continues the series' long-running Samaritan storyline. It centers on the Machine evaluating a list of possible strategies to allow the team to succeed in a mission to recover New York City's stock market after Samaritan attacks the stock exchange and cripples the city's financial system.
According to Nielsen Media Research, the episode was watched by 10.08 million viewers with a 1.7/5 ratings share in the 18 to 49 age demographic upon airing. The episode was highly acclaimed by critics and audiences alike, with reviewers praising the originality and execution of the premise, the thematic value, and the shocking ending, with many calling it one of the series' best episodes.