Netflix is increasing its inventory of high-definition Blu-ray titles while at the same time increasing the price it charges subscribers for them. The amount of the increase, which is set to go into effect on April 27, varies by subscription plan, with the Blu-ray premium for its cheapest plan (one DVD at a time; a maximum of two DVDs permitted per month) costing an additional $1.00 per month; an extra $4 per month for its most popular plan (three DVDs at a time; unlimited rentals per month); and $9 per month for its most expensive plan (eight DVDs at a time; unlimited rentals). Netflix observed that Blu-ray discs cost the company as much as 30 percent more than standard-definition DVDs. News of the price increase boosted shares of Netflix by 6 percent to $42.03 on a day when the overall market suffered another sharp downturn.