Chairman John S.R. Shad of the Securities and Exchange Commission got an early stocking stuffer this month.

The SEC is a frequent host to roundtable discussions with leading figures in merger and investment circles to delve into the gyrations of the corporate takeover world.

But the SEC had no round table. Instead, participants have been arrayed around a box-shaped grouping of ordinary conference tables, creating problems of positional diplomacy.

If Shad is at the head, who must be placed the foot? Frederick H. Joseph, vice chairman of Drexel Burnham & Co., the junk bond specialists? Or former Citicorp chairman Walter B. Wriston? Or Andrew Sigler, chairman of Champion International and a spokesman for big business on takeover issues? How could the SEC avoid charges of favoritism?

Shad passed the word that he wanted a round table and pronto. But the government-issue version would have cost $3,000 or more, SEC spokesman Mary McCue said, a high price even for diplomacy.

The SEC's staff came to the boss' rescue. A round table with room for a dozen or so people was constructed from hardware store plywood. A cover of dignified brown felt was attached. Price: $275, McCue said.

Members of the Council of Institutional Investors sat down with Shad and other SEC officials on Dec. 10 to inaugurate the piece of furniture. No complaints were heard about the order of seating.