Prices of Treasury securities were narrowly mixed in a session that effectively ended shortly after 1 P.M. yesterday, after a fire in lower Manhattan led to a widespread loss of electrical power.
The fire at the Consolidated Edison power plant just moments after the Treasury had conducted its weekly auction of three-month and six-month bills darkened trading screens and computers.
Had the fire not broken out, the auction would likely have been the highlight of an otherwise quiet summer Monday trading session.
''The market was lucky that the power outage happened on a day when not much was going on,'' said David R. Duerson, manager of government securities trading operations at the Security Pacific National Bank in Los Angeles.
At the auction, bids on the three-month bills produced an average discount rate of 7.41 percent, up from the average rate of 7.23 percent at the sale a week ago.
Six-month bills were sold at an average rate of 7.31 percent, up from an average rate of 7.19 percent a week ago.
Trading in the secondary market for Treasury securities continued on a very limited basis after the fire. It all but ended at 3 P.M., Eastern time, when trading in bond futures contracts close on the Chicago Board of Trade.
''We tried to stay open in some limited capacity until the Board of Trade closed,'' said Bruce R. Lakefield, an executive vice president at Shearson Lehman Government Securities.
By late in the day, the Treasury's 8 3/4 percent 30-year bonds of 2020 were offered at a price of 99 17/32, down 1/32 point, to yield 8.79 percent, unchanged from late Friday.
Among note issues, the 8 3/4 percent 10-year notes were offered at 100 17/ 32, down 6/32, to yield 8.66 percent. And the 8 percent two-year notes were offered at 100 6/32, up 3/32, to yield 7.89 percent.
The prices are quotes from a sampling of dealers by a New Jersey office of Telerate Inc., a subsidiary of Dow Jones & Company that provides price information electronically to market participants. The Telerate office was not affected by the power outage.
However, pricing securities was extremely difficult yesterday because three major interdealer brokers, the RMJ Securities Corporation, Fundamental Brokers Inc. and Cantor Fitzgerald & Company, were affected.
At the Chicago Board of Trade, the nearby September bond futures contract closed at 90 23/32, down 5/32 on the day.
''Developments in the Middle East will remain the key theme for some time,'' said Raymond W. Stone, a managing director at Stone & McCarthy Research Associates, a Princeton, N.J. firm that provides research and commentary on developments in the foreign exchange and credit markets.
''But this week all eyes are on the economic data that will be released, beginning with the retail sales report this morning.'' On Thursday reports are due on the Consumer Price Index, industrial production, capacity utilization, housing starts and real earnings.
Mr. Stone and other analysts are projecting that retail sales rose by half a percentage point last month.
A more accurate barometer of consumer sentiment may be announced later in the day, however, when major auto makers are expected to report on how auto sales fared during the first 10 days of August.
''Those numbers will be the first piece of information we will have that bridges the oil price shock,'' Mr. Stone said.
Although the severity of the fire's damage was unknown as market participants went home, many traders said they did not expect that activity would return to normal today. That could create difficulties if unexpected news develops.
''If we come in on Tuesday and the systems are still down, we could have a problem,'' Mr. Duerson said.
Both these issues are dated August 16, 1990. The three-month bills mature Nov. 15, 1990 and the six-month bills, Feb. 14, 1991.