Spain, one of the 34 countries that pledged to join the newly formed Inter-American Investment Corp., confirmed its agreement last week and subscribed to 626 shares of the company.

IIC, an affiliate of the Inter-American Development Bank, was formed in March when member countries subscribed to the quota of two-thirds of the company's shares. The company will finance private enterprise in Latin America.

With the induction of Spain, 23 countries have finalized their membership, representing 70 percent of the company's capital.

The corporation had an initial capital stock of $200 million, divided into 20,000 shares of $10,000 each. Latin American and Caribbean nations are obligated to subscribe to 55 percent of the shares, the United States to 25.5 percent, and countries outside of the region to 19.5 percent.

After the initial offering has been represented, the board of governors has the authority to issue callable capital, in the form of shares, which are guaranteed by member countries to meet the demands of the company. The company also will use dividends and returns on other investments to finance operations.

The board of governors will meet in Caracas, Venezuela, in September to elect a board of directors. Export-Import Bank

The Export-Import Bank, which previously had two main operating divisions, last week reorganized its structure and added four divisions to improve administration and access to its programs.

The bank created the International Lending Division, Country Risk Analysis Division, Policy and Planning Division and Information Resources Division and added the U.S. Division to the Insurance and Banking Division.

The International Lending Division will oversee all of the bank's lending and guarantee activities. Before the change, lending activities, organized according to the type of credit being sought, were divided between two main divisions. According to John A. Bohn Jr., president and chairman, the bank can now handle any request for loans or guarantees from start to finish within that division.