Hi Claudio,
I have the same problem with "GE". If you follow the Wolfram Financial Plattform: Quick Start, by Michael Kelly & Samuel Chen (check below the first lines), you get "Missing["NotAvailable"], for "GE". For all other companies it is fine. So the problem must be in in NYSE and not in Mathematca.
stocks = {"MSFT", "AAPL", "GOOG", "GS", "XOM", "GE"};
properties = {"Symbol", "Name", "Price", "PERatio", "MarketCap"}
data = Table[FinancialData[s, p], {s, stocks}, {p, properties}]
stocktable =
Style[TableForm[data,
TableHeadings -> {None,
Style[#, Bold] & /@ {"Ticker Symbol", "Name", "Current Price",
"P/E Ratio", "Market Cap"}}], FontFamily -> "Verdana", 14]