A 22-year-old man has been arrested after police found him with 53 stolen phones after a Royal Blood gig.
West Midlands Police carried out a "proactive" operation after receiving reports that other concerts by the rock band had seen high numbers of mobile phone thefts.
The man was detained on suspicion of theft in Broad Street, near to the concert at Arena Birmingham, on Saturday night.
Police said the majority of victims had been identified but urged others to get in contact.
"It's an unfortunate reality that large crowds at concerts such as this make rich pickings for career criminals," Detective Sergeant Jeff Clifford said.
"We're hot on the heels of these offenders but you can also reduce your chances of falling victim to such crimes by remaining extra vigilant when attending busy events.
"If you think you had your phone taken last night, please get in touch with us and we can check whether or not we have been able to recover it."
Anyone who believes their phone was stolen at the Birmingham concert should contact West Midlands Police on 101.
People can also record details of their phones and other valuables on the national property register at Immobilise, which can help police reunite stolen items with owners.