When the Mail uncovered a thoroughly rotten deal being offered to thousands of private investors to buy their shares in insurance company Aviva for much less than they are worth, even our seasoned reporters were shocked at the sheer audacity.

It’s also shocking that such a brazen bid to cheat private shareholders has been allowed to get this far.

An obscure US arbitrage company called Litani is circling thousands of Aviva’s private shareholders, offering to buy their shares for a lot less than the market price in a ‘mini-tender’.

It has produced an official-looking letter that mimics standard communications on share issues, takeover bids and the like.

Litani is hoping to profit at shareholders’ expense by openly inviting them to sell shares at a rip-off price, of their own free will. The ruse depends on investors failing to realise they are being had. That could easily happen if they are elderly and vulnerable or unversed in stock market dealings.