Big investments made by Warren Buffett and George Soros, the billionaire fund managers, in the same sector on the same day have attracted the attention of Wall Street.

Berkshire Hathaway group, owned by Mr. Buffet, last week doubled its stake in Comcast, the biggest US cable provider, bringing its holding to 10 million shares worth about $328 million. The same day, Mr Soros bought $50 million in shares in Comcast’s chief rival, Time Warner.

The investments occur at a time of rapid technological changes in the telecommunications sector, with cable companies and telecoms groups fighting for each other’s business using
new technologies such as broadband and internet telephony.

Cable groups such as Time Warner and Comcast have acted aggressively to conquer the telephone market. Meanwhile, telecoms groups such as SBC Communications have taken action, investing billions in an effort to offer television and video content alongside with high-speed internet and long-distance services.

And although some observers are inclined to regard Mr Buffett’s and Mr Soros’s investments as a benefit of the cable companies’ prospects, critics warn that the struggle over America’s phone lines and television sets is far from over.

Shares in cable and telecoms groups have met with mixed fortunes during the past year.

Since the start of the new year the situation has changed. Shares in cable groups remained steady as the market faced a decrease in January. But telecoms shares have fallen sharply despite a string of merger and acquisition activity across the sector.