A new menu at struggling restaurant chain Frankie & Benny failed to whet UBS’s appetite, causing shares to slump to a three-month low in intraday trade.

The Swiss bank downgraded Restaurant Group to “sell” from “neutral” and lowered its price target to 275p from 310p amid heightened fears Frankie & Benny’s recent menu launch is not enough to return the mid-cap group to growth.

Analyst Heidi Richardson said: “The turnaround for Frankie & Benny looks challenging based on the changes implemented so far.”

After analysing the new menu along with 20 competitors, UBS found that Frankie & Benny’s prices have been reduced by an average of 6pc since September, compared with competitor prices, which have increased 4pc over the same period.

The bank said the new menu “remains complex”, with 67 main courses on offer, more than double the average of its rivals.

Richardson added: “With F&B the largest brand, representing over half of the group's store estate, the turnaround of this brand is key to the group's growth recovery.”

Shares in the mid-cap stock dropped 23.7p, or 7pc, to 312.9p.