It was then manufactured by corporate owners until a series of sales and bankruptcies in the 1990s resulted in transfer of production to the Revere, Massachusetts–based New England Confectionery Company (Necco).

In the case of the Clark Bar, the interior consisted of a crispy confection that included ground peanuts around a caramel core.

In late 1990, Leaf announced plans to close its O'Hara facility and move production of two other D. L. Clark candy bars, the Zagnut and P. B. Crunchers, to the Chicago area.

[13][14][15] Pittsburgh-area entrepreneur Michael Carlow purchased D. L. Clark Co. and its remaining brands from Leaf, and combined it with another struggling but iconic local producer, the Pittsburgh Brewing Company and its Iron City beer, as well as a local bakery and a glass manufacturer, plus the Fort Wayne, Indiana-based producer of Bun Bars under the umbrella of the Pittsburgh Food & Beverage Company, continuing production of the Clark Bar in O'Hara.

[16] However, amidst accusations of a check kiting scheme that would lead to Carlow's eventual imprisonment,[17][18] he was forced to relinquish control in 1995, and production ceased.

[16][19] Leaf then foreclosed on a $3 million loan they were still owed, and commenced making Clark Bars at their Illinois facility with an altered recipe.

[22] Challenges with production machinery speed[24] and reproducing the bar's consistency and shape pushed back their reintroduction, but did provide the raw material for Boyer's first Clark-related product, the Clark Cup, a peanut butter cup that originally included ground misshapen Clark Bar in the filling.

[25] Once Boyer resolved these production issues, the Clark Bar was available at the factory outlet in late December 2019,[26] and was released on a limited basis to stores in the Pittsburgh area in mid-February 2020, to be followed first by a full Pittsburgh release, and then sale nationwide,[27][28] but as of December 2021, production was still limited, with distribution only to Pittsburgh-area specialty candy stores.

[29] In part due to its historical association with the military, the Clark Bar is the favorite snack of the eponymous lead in the Amazon Prime Video series, Reacher.