Marks & Spencer is set to be evicted from the FTSE 100 index of Britain's biggest firms.

That's according to Reuters calculations based on Tuesday's (September 3) closing prices.

Declines in its shares mean it's now ranked outside the top 100.

It will be the first time the 135-year-old company has not been part of the blue-chip list.

Though on Wednesday (September 4) morning M&S stock was beating the broader index - up around two percent in early trade.

The shares recovering some losses posted this week ahead of its FTSE expulsion.

They were also buoyed by wider market optimism after lawmakers took steps to avert a no-deal Brexit.

The longer term impact may be less positive though.

For one thing, M&S shares won't now be held by investment funds that track Britain's top companies.

They have already lost about 40 percent of their value since early 2018.

The historic chain has struggled with competition in clothing, food and, particularly, online sales.

Nimbler, younger rivals like Zara and H&M have taken market share.

In response M&S has pressed ahead with a restructuring under chairman Archie Norman.

Now the FTSE reshuffle will be formally announced after the close of trading on Wednesday.

It will take effect on September 23.