A late rally pushed prices into positive territory Thursday on the London Stock Exchange. The Financial Times-Stock Exchange 100-share index rose 0.5 point, or 0.03 percent, to close at 1,841.3. Volume rose to 494.3 million shares from 363.9 million shares traded Wednesday. The market's attention was focused on speculative situations, giving selected stocks a sharp boost, analysts said. The lack of strong interest on the part of fund managers to enter the market, except in these special situations, also gave no incentive for players to pile into new equity positions, they said. The Financial Times 30-share index was up 1.9 points at 1,480.7 at the close. The Financial Times 500-share index rose 2.15 points to close at 1,050.63.