INVESTMENT FIRM BOOSTS PUROLATOR <PCC> STAKE Halcyon Investments, a New York investment partnership that deals mainly in risk arbitrage and stock trading, said it raised its Purolator Courier Corp stake to 726,700 shares, or 9.5 pct, from 474,900, or 6.2 pct. In a filing with the Securities and Exchange Commission, Halcyon, whose managing partner is Alan B. Slifka and Co, said it bought 201,800 Purolator common shares between Feb 3 and March 2 at prices ranging from 28.689 to 34.811 dlrs each. Halcyon, which said it has spent 20.1 mln dlrs for its Purolator common shares, said it also acquired options on Feb 27 giving it the right to buy 50,000 shares for 1.8 mln dlrs.