Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Cincinnati Bell (CBB) plunged today by as much as 10% after subsidiary CyrusOne commenced its IPO.

So what: The expected price range for the offering is $16 to $18, and the company is selling 16.5 million shares. If underwriters exercise their options, CyrusOne could raise upwards of $341 million. CyrusOne is looking to be listed on the Nasdaq under the symbol "CONE."

Now what: The subsidiary contributes nearly 15% of Cincinnati Bell's revenue, and after the deal's completion Cincinnati Bell estimates it will still have approximately a 72% stake in CyrusOne. CyrusOne had said it wants to structure itself as a real estate investment trust. The pricing range is on the conservative side of what investors were expecting, which may be contributing to the drop.

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