Oh come on, please.....
"Apple's share value hit an unprecedented $500bn in pre-marketing trading this morning, making the company worth more than Poland"
Simply not true as any fule kno.
You cannot buy Poland for $500 billion. You can buy Apple for $500 billion (well, alright, maybe a takeover premium).
Because $500 billion is the GDP of Poland. That is, it's the value added in the Polish economy each year.
Apple's $500 billion is the net discounted value of all the value that Apple will produce in the future. This is comparing a flow with a stock.
The accurate comparison is profits plus wages paid for the company as against the GDP of a country. A more accurate comarison would this be that Apple is similar to Luxembourg ($55 billion GDP, couple of hundred thousand people in the labour force).