bolt-on acquisitions in its core businesses, signing a definitive agreement to buy an electronic security business for $1 billion.

The all-cash offer is for SecurityLink, the electronic security systems business of Cambridge Protection Industries, an Illinois-based company founded by GTCR Golder Rauner, a Chicago private equity group.

The deal will add businesses with annual revenues of $500 million and one million customers to Tyco's ADT security business, which has more than three million customers.

Dennis Kozlowski, chairman and chief executive, added that the acquisition continued Tyco's strategy of expanding its base of recurring revenues.

Tyco has rediscovered its acquisitive habits in the past six months, having successfully dismissed the questions about its accounting practices that had weighed on its stock -- its chief acquisition currency -- in 1999.

In March, however, it broke with its pattern of adding to its core electronic components, telecommunications systems and security services businesses with the acquisition of CIT, a large commercial finance group.

Its cash and stock offer for CIT, worth $8.7 billion at the time of the deal, was designed to allow Tyco to offer financing packages to its existing customers, in a similar way that General Electric uses GE Capital.

Some analysts expressed concern about the move beyond Tyco's traditional base and the high premium it paid for CIT, but Tyco's stock has since rallied.

Cambridge bought SecurityLink from Ameritech, a subsidiary of SBC Communications, for an undisclosed price just four months ago. The security systems business, for which no profit details were released, has residential, commercial and government customers.

Mr. Kozlowski said: "As with our existing ADT operations, we expect this business to generate healthy organic growth with attractive incremental margins.'' Tyco said the acquisition should add three cents per share to its earnings in the first year, and it expects ongoing product, service and operational synergies.

In December, Tyco paid $1.15 billion for Simplex Time Recorder, a fire alarm and security systems business.

A month earlier, it bought Lucent's power systems subsidiary for $2.5 billion.

Shareholders of CIT Group Inc. on Wednesday approved the commercial finance firm's $9.2 buyout by Tyco.

The deal gives a financial lever to Tyco, and in return, CIT shareholders get a hefty premium for their stock.

Tyco makes everything from ADT burglar alarms and undersea fibre-optic cable to electronics and plastic hangers. CIT immediately will have as much as $6 billion in new financing opportunities operating under Tyco's vast corporate umbrella, Tyco executives have said.

"Our shareholders voiced their strong support for the recommendation of CIT's board of directors and we are delighted with today's affirmative vote,'' CIT Chairman Albert Gamper Jr. said in a statement.

The deal is expected to close after receiving regulatory approval, which is anticipated by June, CIT said. When announced in March, Tyco agreed to pay a 54 percent premium for CIT shares. Tyco will swap 0.6907 Tyco share for each share of New York-based CIT.

Tyco estimates CIT's operations will add 10 to 12 cents a share to its fiscal 2002 earnings.

Harriet Baldwin, an analyst at Deutsche Banc Alex. Brown, expects even more of an upside. She said Tyco's forecast is conservative because it includes only minimal cost-savings. In past acquisitions, Tyco has been aggressive with cost cutting, such as eliminating jobs and closing facilities.

CIT will pose less risk to Tyco if it is seen and structured as a stand-alone profit center, Baldwin said. Tyco core businesses will have to make their customer deals work without counting on upfront financing fees CIT may get, she said.

Analysts say they will watch closely the nonperforming assets in CIT's portfolio. Baldwin told investors in a research note that she expects nonperforming assets to increase upon more scrutiny of CIT's portfolio.

Tyco shares were off 71 cents at $58 in afternoon trade on the New York Stock Exchange. CIT shares were off 28 cents at $39.77.