MIDEAST STOCKS-Mammoth bond issue boosts Saudi, Egypt rebounds

* Saudi banks rally on bond issue * SEC jumps on strong Q3 profit * STC gains on in-line profit, Mobily drops on loss * Hokair tumbles on earnings slump * Dubai's DXBE jumps for third day before theme parks open By Celine Aswad DUBAI, Oct 20 (Reuters) - Saudi Arabia's stock market rose sharply on Thursday as banks rallied after the kingdom's mammoth international bond sale, which could help to unclog liquidity bottlenecks in the economy. Egypt bounced as investors bought into recent dips. The Sa