BERLIN, Nov 30 (Reuters) - Shares in Siltronic jumped on Monday after the German silicon wafer maker said on Sunday it was in advanced talks to be bought by Taiwan's GlobalWafers in a 3.75-billion-euro ($4.5 billion) deal.

The stock rose by nearly 10% to trade just shy of the offer of 125 euros per share that Siltronic said it expected GlobalWafers to make, describing the proposed valuation as "appropriate and attractive".

That represents a premium of 48% to the undisturbed average market price for Siltronic over the previous 90 days - a gap that was eroded in advance of the deal announcement by a strong share price outperformance.

Siltronic was advised by Credit Suisse, two sources familiar with the matter said on condition of anonymity, in negotiations on the transaction that extended over a number of months.

The Swiss bank's technology analyst, Achal Sultania, in a research note last Friday, raised his price target on Siltronic to 124 euros - 1 euro below the offer price - and reiterated his 'outperform' rating.

Sultania's note cited improved price prospects at Siltronic, saying an oversupply of silicon wafers would dissipate over the next 9-12 months. He did not mention a possible takeover.

Asked to comment, Credit Suisse said it maintained a "strict procedural separation between securities research and investment banking". Siltronic declined any public comment beyond its joint statement with GlobalWafers.

Germany's financial market regulator, Bafin, said it would conduct a routine examination of share price moves in Siltronic before Sunday's announcement. "This is standard practice," Bafin said.

Citi analyst Amit Harchandani said the cash offer reasonably reflected Siltronic's long-term fundamentals but "some on the buy side will be disappointed".

LONG-AWAITED CONSOLIDATION

The market for silicon wafers - the pizza-sized discs on which computer chips are etched - is both competitive and cyclical, putting pressure on smaller players to merge to achieve economies of scale.

The combined companies would be number two in the world market for 300-millimeter wafers, behind Japan's Shin-Etsu . GlobalWafers is currently number four and Siltronic number five.

The Munich-based firm said it expected Wacker Chemie , which owns a 30.8% stake, to agree to tender its shares at the offer price. The parties expect to sign a binding merger agreement in the second week of December.

Siltronic expects to propose a dividend of 2 euros per share for its fiscal year 2020 that will be paid prior to closing.

Nomura is advising GlobalWafers on the transaction, two people with direct knowledge said. ($1 = 0.8365 euros) (Additional reporting by Caroline Copley, Alexander Huebner, Patricia Uhlig and Kane Wu; Editing by Sherry Jacob-Phillips and Barbara Lewis)