Shares in Sulzer, whose chairman is former Siemens CEO Peter Loescher, were trading down 3.7 percent on fears a move from Siemens could derail its plans for a potential merger with Dresser-Rand.
Sulzer said on Wednesday it was in non-exclusive talks with Dresser-Rand.
Germany's Manager Magazin first reported on Friday that Siemens could offer more than $6.1 billion, or $80 per share, for Dresser-Rand.
Dresser-Rand has been rumored as a takeover target for large industrial companies such as Siemens in recent months.
While Siemens has been working with advisers to assess a potential bid for years, it has not made a takeover offer for the company, people familiar with the matter said.
Sulzer, and other suppliers of pumps and valves for mining, oil and construction firms are considered ripe for consolidation. Scotland's Weir Group, for example, tried to buy rival Metso but the deal fell apart over price.
A merger with Sulzer would combine Dresser-Rand's compressors and turbines serving the oil and gas industry with Sulzer's industrial pumps, giving the enlarged group a bigger footprint at a time when a North American drilling boom is boosting demand for energy services and equipment.