Wall Street is beginning to look across the economic valley, picking the stocks to own once the country bounces back from the economic downturn the White House now acknowledges is a recession.
Such hill-and-valley gazing is normal on Wall Street, where pundits claim that anxious investors have anticipated ''six out of the last four recessions.'' But Leslie M. Alperstein, director of research at Bache Halsey Stuart Shields Inc., notes that once a recession is established ''. . . it's appropriate to determine what the economy will look like when it comes out and what kind of investments will be appropriate.''
In Mr. Alperstein's assessment, the White House is a little late in recognizing the downturn. Rather, he believes the economy has labored in a recession for six or seven months. And instead of the normal type of recovery, marked by a 5 to7 percent spurt in growth, Alperstein forecasts continued softness in the first quarter of next year, with a pickup the second half. Real growth, as measured by the gross national product, would be only 3 to 4 percent next year.
On this assumption, the Bache research director thinks it's a good time to reduce cash positions and become more aggressive in the stock and bond markets. But he thinks the market will be more defensive this time, in contrast to earlier periods when the stock and bond markets declined sharply, then rebounded equally sharply. Thus, he recommends a ''threefold strategy.''
First, he advises investors to take advantage of interest-sensitive stocks while interest rates are coming down. This group includes selected utilities, banks, insurance companies, and financial companies.
Second, he says investors should maintain a somewhat defensive position by buying stocks that maintain a good earnings growth rate, such as 12 to 15 percent, compared with those with more explosive earnings potential. Although companies with a greater potential usually outperform the market, they are also more likely to be hurt more by recession.
And third, he would invest in areas of ''clear earnings visibility,'' such as the drug stocks, defense electronics, and to a lesser degree some technology stocks. Alperstein stresses that an investor has to ask himself, ''If the market falls will these stocks survive?''
Richard J. Hoffman, chief investment strategist for Merrill Lynch, Pierce, Fenner & Smith Inc., agrees with Alperstein that the Reagan administration is late in recognizing the downturn. In fact, Mr. Hoffman doesn't believe the economy ever came out of the recession in the beginning of 1980. ''What we've had since January 1980,'' he says, ''is an aberration caused by a volatile Federal Reserve Board policy.'' Thus, he believes the economy is in the process of finishing a recession begun last year. In this part of the downturn, he expects most of the weakness in the capital-goods and export areas.
Like the Bache analyst, Hoffman likes interest-sensitive stocks - utilities, finance companies, and some banks. But he also recommends some high-quality stocks in the consumer area and an investment in long-term US government bonds.
In the consumer sector, he is particularly enthusiastic about stocks that will benefit from the positive effect of the US tax cut on higher-income and two-income families. For example, he would favor companies that make or sell good-quality appliances or furniture, and those that cater to other higher-income shoppers. He'd avoid discount stores.
What stocks would the two analysts avoid at this point? Hoffman says he would not invest in such basic industries as paper, aluminum, chemical, and steel. Alperstein's avoidance list includes international oils, mining, forest products , housing-related stocks, and metals.
To Hoffman, the area of the greatest risk is capital goods. ''It's the area with the most opportunity,'' he says, ''but it is also the riskiest.'' After years of recommending that investors keep their capital fully committed to the stock market, the Value Line Investment Survey is changing its advice. It's telling its customers that when they sell stocks the service rates down, the funds should be invested in the long-term bond market.
The survey reasons that business is slowing down, inflation is subsiding, and high-grade bonds are more undervalued than common stocks. ''In the long run,'' it says, ''stocks will probably give a greater return than bonds, but for the next few quarters stocks may feel the effects of declining business activity, while bonds benefit from that very same condition, which tends to relieve pressure on the credit markets.''
High-grade long-term bonds are now yielding 14 to 18 percent. Should the long-term interest rate fall by one percentage point, high-grade bonds would appreciate by 6 to 7 percent. Added to the yield, investors could get a total return of 20 to 25 percent.
%The stock market tried to mount a rally last week but wavered and fell back. Analysts cited concern about a large large government financing coming up next month and continued concern about the depth of the recession and its effect on corporate profits. For the week, the Dow Jones industrial average sank 13.70 points, closing at 837.99.
Once again takeover stocks were the most active. Newmont Mining rose and then fell sharply after it reached an agreement with Consolidated Gold Fields that allowed Gold Fields to acquire only 26 percent of Newmont's stock. Penn Central was also active, rising and falling sharply. The stock dipped after a federal judge denied an attempt by some dissident Penn Central shareholders to block the company's acquisition of Colt Industries.