TROY – The Troy engineering technology developer Altair Engineering Inc. Monday announced the closing of its initial public offering. The company said its stock underwriters fully exercised their option to purchase an additional 1.8 million shares of Altair Class A common stock, indicating strong demand.

After the underwriters’ exercise of the option to purchase additional shares, Altair sold 9,865,004 shares of stock and a group of existing shareholders of the formerly private company sold 3,934,996 shares. The price to the public was $13 a share, meaning the sale raised a total of $179.4 million.

Sellers included co-founder and CEO James R. Scapa, who sold more than 1.7 million shares, raising nearly $21 million, according to MarketWatch.com.

The company said it would use the proceeds to pay down debt, and is open to further acquisitions. The registration statement for the stock sale was declared effective by the federal Securities and Exchange Commission on Tuesday, Oct. 31. The statement may be viewed at www.sec.gov.

Altair shares opened for public trading just after 10:30 a.m. Thursday at $17 a share, 31 percent above its IPO price. It rallied further Friday to close at $19.37. It closed Monday at $18.97 a share, down 40 cents, or 2.1 percent, on the day. Major market indices rose Monday.

Nasdaq records show the offering had expenses of $4.12 million.

Altair, founded in 1985, produces software and services for simulation, design, supercomputing, and other uses. It has more than 2,000 employees in 68 offices in 24 countries, serving about 5,000 corporate clients. It also has product design and LED lighting subsidiaries.

J.P. Morgan Securities LLC, RBC Capital Markets LLC and Deutsche Bank Securities Inc. acted as bookrunners for the offering. William Blair & Co. L.L.C., and Canaccord Genuity Inc. acted as co-managers for the offering.