Glenn works as an equity trader. He is Julia Sullivan's fiancee, and it is apparent from the beginning that he is not right for her. He is inconsiderate, unloving, and flirts with other women. In a private conversation he admits his reasons for marrying Julia are that she would make a good trophy wife and that a woman like that ought to be on the arm of a powerful financier. When asked if he will regret sacrificing casual sex for monogamy, Glenn confides that he will commit adultery on the sly; his career allowing for extensive travel and figuring Julia will never find out, or maybe tolerate it as being the price for marrying a high-powered man.
Julia is unsure of marrying Glenn; namely due to parental pressure. Julia's parents strived to pay the bills and put food on the table in their early years, and they worry she is doomed to a fate of similar squalor with her struggling as a waitress. Glenn, they say, can provide her with a life they could only dream of. One of Julia's reasons is the disgust with her new name "Julia Gulia", and reflects on her nascent attraction to Robbie by calling herself "Mrs. Julia Hart".
While Glen and Julia on the way to Las Vegas for their wedding, Robbie Hart, the main protagonist who is also in love with Julia, sings a heartfelt love song for her, while Billy Idol subdues Glen in an airplane bathroom. Robbie and Julia are then happily married. What happened to Glenn after that is unknown, although the audience is given hints with his attitude and outlook to the future. Glenn is often shown telling Robbie and the friends of Robbie how he has life figured out, and he is predicting a future of years of prosperity into the 1990s. What Glenn is failing to see is Wall Street Crash of 1987, a.k.a "Black Monday" (occurring two years after the events of the film), which is partly due to his own arrogance in failing to anticipate and prepare for bleak times. It is highly likely Glenn found himself unemployed as many equity firms were bankrupted by the crash.