LONDON (Bloomberg) – Aquarius Platinum Ltd., the fourth- biggest platinum producer in the world last year, rose the most in four months in London trading on plans to raise as much as $249 million from bond and share sales to buy Ridge Mining Plc.

The stock climbed as much as 24 percent to 227.25 pence, the biggest gain since November 24. It traded at 214.5 pence as of 11.19 a.m. local time. Ridge jumped 22 percent to 63.5 pence.

Aquarius may sell more than 46.3 million shares and offer a convertible bond to fund the proposed Ridge deal, Bermuda-based Aquarius said in a statement yesterday. It may offer one share for every 2.75 Ridge shares, valuing Ridge at £63 million ($92 million).

The fundraising "should put the company balance sheet in a strong position with net cash," London-based Liberum Capital said in a note today. "We see this as a de-risking event."

Aquarius signed an initial accord to buy Ridge last month. Platinum producers in South Africa, the source of almost 80 percent of world supply, may combine this year, Stuart Murray, Aquarius's chief executive officer, said last month. Demand for the metal, used in auto pollution-control devices and jewelry, plunged last year as the economic slump eroded vehicle sales.

"Aquarius is being prudent in raising money to help service its current debt of $158 million and to help" its offer for Ridge, Evolution Securities said in a research report.

The share sale is being managed by Merrill Lynch & Co. and Euroz Securities Ltd., while the convertible bond sale is being managed and underwritten by Rand Merchant Bank.