Shares of Tyco International and its spun-off units, Covidien and Tyco Electronics, declined on Monday in their first official day of trading as separate entities.
Tyco Electronics' shares were off 6 cents at $39, and Covidien stock was down 12 cents, or 0.3%, at $42.98 in early trading on the New York Stock Exchange.
Both Tyco Electronics and Covidien had earlier been in positive territory.
Tyco International shares slipped 9 cents to $52.91 in early composite trading.
All three companies' shares trade on the Bermuda and New York exchanges.
Following the spin offs, Tyco International's main businesses will be in the fire, security and engineered-products markets, while Tyco Electronics makes electronic components and Covidien makes medical products, including supplies and pharmaceuticals.