But, where some experts see recovery, others see just a speculative bubble.

Analysts at Goldman Sachs have dismissed the speculative bubble argument.

For now, market authorities appear more worried about falling share prices than a new speculative bubble.

For now, the risk is mitigated by a big commodity price retreat from 2011's speculative bubble.

Fellow value investor Howard Marks thinks it's a speculative bubble, as does hedge fund icon Ray Dalio.

The recession was caused by the collapse of a speculative bubble driven by bankers and the finance sector.

The bank also warned that the housing market could be heading for a " speculative bubble" and that inflation remains a concern.

True, the crisis - the result of a speculative bubble - concerned the banking and real estate markets rather than the capital markets.

The market was also unsettled by Bundesbank council member Mr Franz-Christoph Zeitler, who warned that a speculative bubble might be emerging in German equities.

Analysts say classifying some CDS as insurance would reduce the speculative bubble by helping to identify the investors with real credit exposures to hedge.

Neil Wilson, a senior market analyst at ETX Capital in London, says bitcoin is "following the playbook for a speculative bubble to the letter".

Chavez also said oil prices were being influenced by a " speculative bubble", the collapse of which could send prices as low as $70 per barrel.

Society ends up wealthier but returns drop, though speculative bubbles tend to rise.

Successive speculative bubbles cause misery when they burst, even if it is of our own making.

Of course, speculative bubbles eventually fall back to earth like Icarus, the mythical boy with wax wings.

The speculative bubbles in many Internet, mobile phone and biotech stocks have become as evident as in 1999.