Semtech Corp. and PS Business Parks have been added to the S&P MidCap 400 index.

The Camarillo semiconductor manufacturer and Glendale real estate company joined the index on April 4. The S&P MidCap 400 has become the most widely followed mid-cap index since its launched in 1991, according to S&P Global, the company behind the index.

Inclusion on the S&P 400 requires a market capitalization between $1.4 billion and $5.9 billion. Semtech’s market cap was at $3.5 billion while PS Business Park’s was at $5.2 billion.

Other San Fernando Valley area companies on the S&P 400 include Calabasas staffing company ASGN Inc.; Calabasas restaurant chain Cheesecake Factory Inc.; and Teledyne Technologies, an aerospace, marine and digital imaging products manufacturer in Thousand Oaks.

Shares of Semtech closed Monday down 34 cents, or a fraction of a percent, to $52.57 on the Nasdaq while PS Business Parks closed down 51 cents, a fraction of a percent, to $149.34 on the New York Stock Exchange.