SHARES in Italian high tech group, Olivetti, went into freefall on the Milan stock exchange yesterday after a two day suspension was lifted, forcing exchange authorities to step in again and halt trading. The crisis hit group's stock price slid to below 600 lire (24.5p), triggering an automatic suspension in the afternoon under exchange rules limiting price movements to 20 per cent either way, the stock market council said. Trading failed to start again and dealers said it was expected to get under way again this morning.