(Reuters) - Shares in ViacomCBS fell sharply and Discovery Inc stock swung between gains and losses on Monday after steep declines last week triggered by a hedge fund defaulting on margin calls.ViacomCBS shares traded down 3.4% at $46.58 after hitting a low of $43.00 while Discovery was up 2.3% at $42.85 after hitting a low of $39.82 earlier in the session. Both stocks plummeted by about 27% on Friday. Losses at Archegos Capital Management, run by former Tiger Asia manager Bill Hwang, triggered massive stock sales on Friday, according to a source familiar with the matter. Shares in both companies ended last week around 50% below their most recent highs. Investors had been betting heavily on the companies’ new streaming services. Among the factors that may have added additional pressure to shares of ViacomCBS, which hit a peak of $101.97 earlier this month, was the March 22 sale of 20 million Class B common shares at $85 and its offering of $1 billion of convertible preferred stock, investors said. When a company expands its number of shares, the value of existing equity is diluted, which tends to coincide with a market share price decline. “People are finally realizing valuation does matter, that things were overhyped on the streaming side of things and the equity offering from ViacomCBS was a wake-up signal,” said Craig Huber, an analyst covering the company at Huber Research Partners in Greenwich, CT. “ViacomCBS management took advantage of the much higher prices, to their credit,” Huber said. Nomura and Credit Suisse are facing billions of dollars in losses after fund, identified by sources as Archegos Capital, defaulted on margin calls, putting investors on edge about who else might have been caught out.