The index of leading indicators, designed to forecast economic activity six to nine months ahead, climbed 0.8 percent to a new high in May, the Commerce Department reported.

West Germany's two largest banks, Deutsche Bank and Dresdner Bank, signed an agreement to lend the Soviet Union 5 billion deutsche marks ($2.98 billion) for reconstruction of the Soviet economy. The two banks will be lead managers of a consortium of banks that will provide the funds.

Salant Corp., an apparel maker, sought bankruptcy protection after struggling unsuccessfully with debts incurred in buying Manhattan Industries, a larger rival, two years ago. It was the second filing under Chapter 11 for the company, whose brands include Dr. Denton sleepwear, John Henry shirts and Lady Manhattan sportswear.

A penny stock reform bill was approved by the House Energy and Commerce Committee. The bill would give the SEC authority to bar crooked promoters and consultants from selling the speculative stocks. The panel also approved a securities-law reform act that would widen the SEC's authority to seek court orders.

Walt Disney Co. said it soon will start shipping a new talking software package to teach basic reading and counting skills on personal computers to children ages 2 to 5.

The National, the daily sports newspaper, plans to expand to 13 markets from its current four by April 1991. The schedule through the end of the year calls for editions in Washington- Baltimore, San Francisco, Dallas, Detroit, Boston and Miami-Fort Lauderdale. The three sites for early 1991 have not been announced.