Gershkovich, 32, was arrested March 29, 2023, while on a reporting trip to the Ural Mountains city of Yekaterinburg.
Authorities claimed, without offering evidence, that he was gathering secret information for the US.
He pleaded not guilty, according to the court, and The Wall Street Journal and the US government have called the trial a sham.
Gershkovich appeared in court for a second straight day on Friday as the closed-door proceedings in Russia's highly politicised legal system picked up speed.
Reporters had no access to the courtroom this week and Evan Gershkovich wasn't seen. (AP PHOTO)
A verdict is expected later in the day, according to court officials.
Unlike previous sessions in which reporters were allowed to see Gershkovich briefly before sessions began, there was no access to the courtroom this week and he was not seen, with no explanation given.
Espionage and treason cases are typically shrouded in secrecy.
Court officials said the prosecutors requested an 18-year sentence in a high-security prison during closing arguments.
"Evan's wrongful detention has been an outrage since his unjust arrest 477 days ago, and it must end now," the Journal said in a statement on Thursday.
"Even as Russia orchestrates its shameful sham trial, we continue to do everything we can to push for Evan's immediate release and to state unequivocally: Evan was doing his job as a journalist, and journalism is not a crime. Bring him home now."
The US State Department has declared Gershkovich "wrongfully detained", committing the government to assertively seek his release.
Russian Foreign Minister Sergey Lavrov said on Wednesday that Moscow and Washington's "special services" were discussing an exchange involving Gershkovich.
Russia has previously signalled that verdict would have to come before any exchange.
Even after a verdict, any such deal could take months or years.
State Department deputy spokesman Vedant Patel on Thursday declined to discuss negotiations about a possible exchange but said: "We have been clear from the get-go that Evan did nothing wrong and should not have been detained.
"To date, Russia has provided no evidence of a crime and has failed to justify Evan's continued detention."
Gershkovich's trial began June 26 in Yekaterinburg after he spent about 15 months in in Moscow's notorious Lefortovo Prison.
The Russian prosecutor-general's office accused the journalist of "gathering secret information" on orders from the CIA about Uralvagonzavod, a plant north of Yekaterinburg that produces and repairs tanks and other military equipment.
Gershkovich's employer and US officials have dismissed the charges as phoney.
Russia's interpretation of what constitutes high crimes like espionage and treason is broad, with authorities often going after people who share publicly available information with foreigners and accusing them of divulging state secrets.
Arrests of Americans are increasingly common in Russia, with nine U.S. citizens known to be detained there as tensions between the two countries have escalated over fighting in Ukraine.
