(Sharecast News) - Citi downgraded Great Portland Estates on Wednesday to 'sell' from 'neutral' as it argued that stock weakness will deepen before long-term value arises.

The bank said it estimates that office values will fall further and that the stock could overshoot to the downside as negative values materialise, "and potentially discount opportunistic equity".

Longer term, Citi said it continues to expect a once-in-a-cycle buying opportunity for office assets and anticipates GPE taking advantage of its de-leveraged balance sheet positioning and operational platform and cyclical expertise into the end of the cycle.

"We raise the possibility that the scale of opportunity may lead to new equity providing a strong path to both returns and risk management," it said.

"Given that downside risks would appear a nearer term risk and a prerequisite for opportunistic acquisitions and outsized returns to be harvested in the next cycle, we estimate near-term stock weakness as the final phase of downside risks playing out this cycle."

At 1035 GMT, the shares were down 5.3% at 369.20p.