World Economy is worth $1,400 Trillion which includes Stocks, Real estate, Bonds, Commodities and I think Derivatives also. USA real estates are worth $23 Trillion. If 45% of world's wealth is destroyed, it means $650 Trillion has been destroyed. In other words, world economy has suffered losses of $650 Trillion.
I think it's false statement - from economics perspective all what happened here - is just simple price level adjustment rather than real wealth destruction. Bubble part were reduced mostly, and partially real economy suffered too, but in general real economy delta is actually too small relative to bubble part. IMHO.
For an "asset" to become "overvalued" such as stocks, real estate, commodities, the equivalent amount of "real money" or "cash" has to be invested into that asset. Example, USA real estate are worth $23 Trillion which means "$23 Trillion cash" has been invested into USA real estate so it is over-valued to $23 Trillion. Only when "actual cash" is invested into an asset equivalent to the monetary over-valuation, the asset becomes over-valued to that extent/amount. So, if world economy was worth $1,400 Trillion. This means $1,400 Trillion "real cash" has been invested. Ultimately now, world economy has suffered $650 Trillion "real cash losses"
Ain't seen NOTHIN' yet! The markets are still in the "downside speculation" phase. The "OMG, we're FUCKED" phase is still in the wings.