Sir Martin Sorrell has defended his behaviour while in charge of WPP in an exclusive interview with the BBC.
The Wall Street Journal is reporting that Federal prosecutors in Manhattan have opened an investigation into media-buying practices in the advertising industry and have begun issuing subpoenas.
The story is here and appears to be moving share prices in media companies. FTSE 100 advertising company WPP is 2.8% lower while in France Publicis is off 2.7%.
Sir Martin Sorrell will make his return to the London Stock Exchange today when shares in his new business S4 Capital Group will re-list.
The former boss of WPP who stepped down after an internal investigation into claims of personal misconduct, says the business will provide "global, multi-national, regional, local clients and influencer-driven millennial brands with new age/new era digital marketing services".
Shares in S4 were up 1.5%.
Shares in the world's largest advertising agency plummeted this morning.
WPP is trading 7% lower.
The company revealed lower revenues in its first-half results - but also raised its sales expectations.
Insider candidate Mark Read was confirmed as chief executive yesterday.
He takes up the role at a difficult time for WPP, which issued a number of warnings about growth last year.
The firm faces intense competition from the likes of Google and Facebook as more advertising moves online.
Advertising giant WPP has announced the appointment of Mark Read as chief executive, the company's former head of operations.
He replaces Sir Martin Sorrell who quit in April amid accusations of misconduct.
Mr Sorrell was often criticised over the size of his pay awards, which in 2015 hit £70m.
WPP says Mr Read will receive an annual salary of £975,000, with an annual bonus of up to 250% of salary.
Miners dominate the FTSE 100 fallers this morning, led by BHP Billiton down 1.3% at £16.78.
Advertising giant WPP is the biggest blue chip riser, up 1.8% at £12.46.
The wider FTSE 100, however, has trimmed gains and is now up 3.06 points at 7,614.70.
Shares in Hikma Pharmaceuticals soared by 8.6% to £17.88 on the FTSE 250 after it raised its sales forecast for the full-year.
It said it had sold more injectable opioids in the US and had a better-than-expected performance in generics for the first half of the year.
The FTSE 250 rose 0.29% to 20,568.95.
There are few stocks heading upwards on the FTSE 100 this morning.
Advertising giant WPP is leading the blue chip risers, up 1.6% at £11.74.
GlaxoSmithKline is also up, 0.99% at £15.64 ahead of its results on Wednesday when the pharmaceutical group's chief executive Emma Walmsley (pictured) will provide a strategy update.
easyJet is the biggest faller on Monday morning - its share price is down 2.3% at £15.76.