With the number of HDD companies likely to fall to 3 by next year (with the Western Digital acquisition of Hitachi GST) it will be interesting to see if either Western Digital or Toshiba (the other HDD manufacturer) will introduce their own hybrid HDD products.

FORBES: New Seagate Solid State Hybrid Drive is Faster and Vaster

If we take 2010 aggregate company unit shipments and add the unit shipments of Seagate to Samsung and Western Digital to HGST, we find the combinations should have resulted in about 41% unit share for Seagate plus Samsung, 48% unit share for Western Digital plus Hitachi GST and 11% unit share for Toshiba.

FORBES: Why Government Regulators Should Approve Hard Disk Drive Company Consolidation

In short, Seagate and Western Digital are both getting hit this morning.

FORBES: Disk-Drive Stocks Sag As Hutchinson Warns On Weak Demand