Investors are preparing for travel giant Tui to count the cost of problems with the Boeing 737 Max aeroplane on Tuesday, as it updates the market on spring and summer trading.

The group is expected to detail its contingency plans after the aircraft was grounded in the wake of the Ethiopian Airlines crash in March in which 157 were killed, months after the Lion Air crash in Indonesia in which 189 died.

Tui's fleet, which comprises around 150 aircraft, currently includes 15 grounded 737 Max planes for the UK, Belgium, the Netherlands and Sweden.

Meanwhile more favourable market conditions are expected to boost bookings, though this may be driven by discounts which affect the group's margins.

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Analysts at Numis estimate that underlying earnings for the third quarter excluding the cost of the Max problems will come in at €148 million (£137.4 million), down 20%, due to tighter margins.

Demand for Winter holidays looks set to be subdued by political uncertainty ahead of the October 31 Brexit deadline.

Analysts at The Share Centre said: "It is fair to say it's been a difficult year for tourism group Tui due to a range of factors including the grounding of the Boeing 737 Max planes.

"In this Q3 report the market will be looking for an update on the expected impact of that issue on Tui's full-year earnings.

"Investors will also be hoping for an improvement in the struggling tour operating business and watching the performance at the hotels and cruises operation which has been better of late."

Advertising firm WPP led Friday's FTSE 100 firms as its shares jumped after it performed ahead of analyst predictions.

Investors cheered the beleaguered firm's revenue performance as its major turnaround programme gathered pace in the second quarter.

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The company, which was left struggling after a string of client losses following Sir Martin Sorrell's exit last year, limited its revenue decline to 1.4% for period.

Meanwhile the company saw pre-tax profits fall 44% to £478 million, as it was hampered by a £138 million one-off tax charge.

The advertising firm has introduced a turnaround strategy intended to simplify its business, which also resulted in the sale of its 60% stake in analytics business Kantar, which it sold to Bain Capital for £3.2 billion.

Shares in WPP were up 8.1% at 989p.

Drugs giant AstraZeneca saw shares push higher after it told investors that its top-selling drug, Tagrisso, had significantly helped patients with a specific type of lung cancer live longer without the disease worsening, following new testing.

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It revealed the positive results from the study of patients with epidermal growth factor receptor-mutated metastatic non-small cell lung cancer.

At present, Tagrisso has been approved in 74 countries - including Japan, the US, and the EU - as a first line treatment for the variant of lung cancer.

It comes after the drugmaker said on Wednesday its cancer drug, Lynparza, was successful in helping patients with metastatic prostate cancer and certain genetic mutations live longer.

Shares in the company were up 2.7% to 7,422p.