BUZZ-RSA Insurance: Market cheers 550p offer from Zurich
** RSA Insurance (LSE: RSA.L - news) top gainer on FTSE 100 on a 550 pence all-cash takeover proposal from Zurich Insurance (Xetra: ZFI1.DE - news)
** Offer values RSA at 5.6 bln stg
** More than half of stock's moving avg traded in the first 15 minutes of trade
** Stock hits early August highs of 528p
** 550 pence offer proposal is 11 pct premium to RSA's closing price on Monday
** If the deal goes through, it will mark one of the biggest insurance deals in Europe (aashika.jain@thomsonreuters.com)