Big UK insurer Aviva has parted company with Kiwi chief executive Mark Wilson, effective immediately, and given itself four months to find a successor.

The manner of his sudden departure after almost six years may look harsh, but it's not hard to see why.

The shares have trailed peers at home and abroad in recent years. Wilson's successor might not need to change strategy substantively, just simply execute it better than he did.

Shares of Aviva — which had fallen 8 per cent this year — rose as much as 2.3 per cent on Tuesday's announcement, despite the company being left without an official chief executive.


Chairman Adrian Montague will temporarily take the reins, backed up by three executives.

This looks like a board moving quickly to placate investors' performance concerns.

"When I joined Aviva, the company was in poor health. Aviva is very different today. I have achieved what I wanted to achieve and now it's time for me to move on to new things," Wilson said on Tuesday.

Wilson, who grew up in Rotorua and studied at Waikato University, had a mixed bag in terms of performance and stakeholder relations during his reign.

There have been some obvious improvements since 2013. Net profit doubled between then and 2017, and Aviva paid out dividends at a bumper rate.

The 2016 purchase of Friends Life Group for about £5.8 billion ($11.8b), unpopular at the time, has been a great source of savings and market-share growth. Analysts rate Aviva highly.

The downside is that dividends and buybacks haven't been able to counteract growing competition and a slowdown in Aviva's core insurance business.

Aviva's first-half operating profit fell 2 per cent, and net income tumbled by 47 per cent — yet the insurer lifted dividends by 10 per cent.

With an inferior capital position to some of its competitors, Aviva's confidence in its ability to do everything at the same time — pay dividends, buy back shares, seal deals and repay debt — seemed optimistic.

The firm has also not grown as fast as its closest rivals Prudential and Legal & General, and the share price hardly moved on.

Some of Wilson's moves outside of the executive suite also weren't to everyone's taste. In March, he joined the board of BlackRock, the world's biggest asset manager, stirring doubts about his commitment to the job at Aviva.

And a ruckus over Aviva's plan to buy back pricey hybrid debt led City firms to take a dimmer view of Wilson, even if he eventually backed down from the idea.

Are there bold new strategic shifts to make? Perhaps some of the £3b earmarked for spending should be more selective, and tilted towards growth and reinvestment.

Aviva relies on the UK for almost two-thirds of operating profit, according to Bloomberg Intelligence, so expanding abroad might be a good bet.

On the other hand, a radical turnaround seems unlikely given Aviva's size and capital-preservation needs.

In the end, this looks like a good move for Aviva.

The big strategic question remains unanswered, but in the short term, no chief executive looks better than an unloved one.

The insurer said the search for a new boss was expected to be completed within the next four months. Wilson will advise the company until April next year.

The decision to replace him is understood to have followed months of discussions, but one source insisted his exit was unrelated.

The silver lining for Wilson is that he will pick up £6 million in pay and benefits as a result of being ousted.