Investing.com -- Shares in Smiths Group fell over 6% to a six-week low on Friday after the British industrial engineer's first-half results showed continuing operations missed analyst forecasts, overshadowing a plan to return an additional £1.5 billion to shareholders.

The stock closed at 2,212 pence, its lowest since early February, extending a 15-day decline from a 52-week high of 2,746 pence hit on Feb. 27.

Smiths reported headline group operating profit of £248 million for the six months ended Jan. 31, up 5.6% from £234 million a year earlier, on group revenue of £1.44 billion, up 2.2% from £1.41 billion. Organic revenue growth was 4.0%.

For continuing operations, John Crane and Flex-Tek, revenue fell to £915 million from £924 million a year earlier, with organic growth of just 0.4% against a Jefferies consensus estimate of £963 million. Operating profit of £181 million was flat year-on-year, with margin up 20 basis points to 19.8%.

Jefferies, which rates the stock "hold," said continuing operations results were "slightly below consensus" and forecast that street estimates would "drift lower."

Stifel, which carries a "buy" rating with a 2,650 pence price target, called trading "more or less in line" at the group level but acknowledged continuing operations were "a little lighter."

Chief Executive Roland Carter struck a forward-looking tone. "We delivered increased momentum in the second quarter, and improved second-half performance," he said, guiding for full-year organic revenue growth of 3%-4% for continuing operations and second-half growth within the medium-term 5%-7% target.

John Crane posted organic revenue growth of 2%, up from a marginal first-quarter decline, with operating margin improving 30 basis points year-on-year to 23.2%. Flex-Tek organic revenue declined 2%, with U.S. construction weakness offsetting aerospace growth of 10.1%. Flex-Tek margin fell 40 basis points to 20.4%.

Operating cash conversion fell sharply to 78% from 94% a year earlier, reflecting a working capital build. Net debt rose to £843 million from a ratio of 0.5 times headline EBITDA a year earlier to 1.2 times, driven by a €650 million bond issuance and share buybacks.

Smiths agreed to sell its detection unit to CVC Capital Partners for £2 billion and Smiths Interconnect to Molex for £1.3 billion, a combined £3.3 billion. Following a £1 billion buyback currently underway, Smiths said it would return the additional £1.5 billion to shareholders post the Detection close via a tender offer, special dividend, or further buyback.