LONDON -- This morning, broker Investec awarded Imagination Technologies Group (LSE: IMG.L) a "buy" rating -- upon which the shares promptly plunged 9% to 473 pence. A coincidence, yes -- and a reminder that Imagination's shares are volatile, linked to both the fortunes of Apple and the macroeconomic health of the economies where Apple's pricey products are sold.

No matter: A 9% fall was small beer for long-term investors, who have already seen Imagination deliver a 19-fold rise in just four years. And today those long-term investors were joined by a fair number of the retail clients of stockbroker TD Direct Investing, whose buying actions made the share the third-most popular purchase between the market's opening and noon. That said, the share is on a price-to-earnings ratio of 64 -- far too rich a rating for me, I confess.

The fifth-most popular purchase by the retail clients of TD Direct Investing between the market's opening and noon was an altogether more staid business -- well, these days at least. In short, Royal Bank of Scotland (LSE: RBS.L) had investors pressing the "buy" button.

Why? As with other banks, the Bank of England's 60 billion pound lending scheme is creating a positive backdrop, and a eurozone-inspired fall in the share price to 257 pence doubtless helped as well. But more particular, perhaps, was a speech by chief executive Stephen Hester. The bank is well on the way to full recovery, he told a City audience at a bankers' conference, predicting that dividend payments would resume next year.

The eighth-most popular purchase by TD Direct Investing's individual clients this morning was Aviva (LSE: AV.L). Investor sentiment was clearly boosted by a just-issued "overweight" rating from JPMorgan Chase. On a forecast P/E of just more than six and a forecast yield of 8%, the attractions -- and risks -- of buying Aviva at today's price of 319 pence are obvious. But incoming chairman and interim chief executive John McFarlane insists the insurer will try hard to maintain the dividend, and that's clearly the message investors want to hear.

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Investing ideas from Malcolm Wheatley: