SeeBeyond, a provider of business integration software based in Monrovia, Calif., had revenue of about $167 million during the last 12 months and has 2,000 customers worldwide.
In premarket trading, shares of SeeBeyond were gaining 85 cents, or 26%, to $4.13. The stock's 52-week high is $4.20. Sun was adding 2 cents to $3.71.
Sun said the products and services offered by the companies are complementary with little overlap. The company expects to complete the purchase this fall.