Market Report: Mittal's sell-off puts skids under Ophir

What does Britain's richest man know that the City doesn't? The Indian steel tycoon and Queens Park Rangers part-owner Lakshmi Mittal sold part of his stake in the mid-tier listed and African-focused Ophir Energy and the shares fell 44.5p to 475p.

Och-Ziff Capital Management and Mittal Investments sold around half their stake – around 9 per cent – amounting to 36 million shares at a price of 475p, raising £171m.

Mr Mittal, who backed the float of the company back in 2011, and Och Ziff have agreed to a 90-day lock-up period for the rest of their stake.

The company has seen a number of investors take profits after its shares gained more than 50 per cent during 2012.

Bank of America Merrill Lynch's Alexander Holbourn said: "While we recognise that there is material value within the portfolio, we believe that the value of the core asset in Tanzania is now being called into question.

"The placing of a combined 9 per cent stake by two pre-IPO shareholders is also a cause for concern."

He gave the shares a hold rating with a price target of 700p.

The news of Mr Mittal and Och Ziff's sell-off came as the group reported good news from its well in Tanzania. A well on the Mzia field in Tanzania, where it holds a 40 per cent stake with BG Group, down 24p to 1,111p, found gas. It is now starting flow testing but warned that the rate may be constrained.

On the benchmark index, investors were trying to remain positive, but eurozone concerns held back any real gains during morning trade.

By the afternoon a speech from Mario Draghi, president of the European Central Bank, who stressed continuing weakness in the eurozone, sent the index into negative territory. Views from Bank of England Governor-elect Mark Carney also contributed to the pessimism and the FTSE 100 lost 66.92 to 6,228.42 – the lowest it has been since 23 January.

Traders were rehashing bid rumours for the energy group Aggreko. The old rumour that ABB Swiss may be taking a look was dismissed by one trader and some suggested a seller was trying to push the price up. The shares' power was cut by 11p to 1,557p.

The catering group Compass was top of the table after a good first quarter with both its North America and emerging-market businesses doing well, and the shares gobbled up 14p to 779.5p.

Conversely, news of a boardroom shake-up and concerns about Chinese growth weighed on the luxury brand Burberry. Industry experts put the large share-price drop down to fears of a change in Chinese law on luxury goods advertising, which could hit the sector's hopes for growth. The shares stumbled 93p to 1,337p.

Back on the mid-tier index, the milk and cheese maker Dairy Crest disappointed the deal-hungry City by admitting that it has no plans to stock up its food cupboard.

Instead of embarking on a food fest to add to its Cathedral City cheese and Clover brands, chief executive Mark Allen said he will spend the money they raised when it sold the French spreads business St Hubert on "internal capital projects", and will "restructure" the balance sheet.

This might be sensible stuff, but it is certainly no way to excite the City.

Panmure Gordon's Damian McNeela is so disappointed with the news from the milkman that he has slashed his rating from buy to hold.

Mr McNeela does admit that "restructuring the balance sheet clearly has its merits and repaying debt is likely to be earnings enhancing," but he says this is "clearly not to the same degree as an acquisition". He upped his price target to 430p but shares were off 14p to 408p.

The online gaming software specialist Playtech was boosted by its 29 per cent stake in William Hill Online, the joint venture which is likely to be bought in full by the bookmaker William Hill. Playtech reported a 51 per cent rise in income and the shares triumphed 8.2p to 489.7p.

Traders were still gossiping about the inter-dealer broker Tullett Prebon. There was vague gossip it might be looking at a possible merger again – after talks with the British-born but New York-based billionaire trader Mickey Gooch's GFI – but shares edged back 3.8p to 268.7p.

Pub group Punch Taverns toasted a 2.25p gain to 13p after it said that it has potentially identified a solution for its capital structure.