(Sharecast News) - Citi upgraded its stance on Great Portland Estates on Friday to 'buy' as it said it was the most attractive time to buy in the last decade.

The bank said the bifurcation of the West End office market is likely to intensify demand for prime core West End office space as tenants increasingly trade up the quality curve.

"This is likely to overwhelm prime development supply aiding development opportunity more than rental growth.

"This increasingly plays into GPE's cyclical timing and development strategy where the stock price is underestimating the scale and profitability of the repositioning opportunity relative to GPE's size."

It also noted the stock is trading at levels below the value of low grade West End offices and comparable to troughs of 2009, undervaluing GPE's portfolio, platform and opportunity, with potential for a cyclical recovery.

At 1010 GMT, the shares were up 1% at 309p.