Unit sales were virtually flat in 2015, according to IRI data, while price increases have pushed up the value of the category less than 1% in the past year.
The weak performance is largely down to decline in private-label products, which account for more than a fifth of the market and fell by around $15m overall across the year.
In contrast, sales of category giant Quaker Oats Company grew 3.7% - or $28m overall – in 2015, driven by a strong performance from the core Quaker oatmeal range that accounts for just shy of half the hot cereals market.
Second-placed brand Cream of Wheat - which owner B&G Foods recently extended with 'To-Go' instant pots - dipped by value and unit sales in 2015.
Quaker Protein - close to $20m
Quaker sub-brands have fared less well than the core range, with most in decline according to IRI data. The exception was the on-trend Quaker Protein instant oatmeal that was launched in November 2014 and raked in almost $20m in its first full year on shelf.
IRI analysts flagged up the launch as a good example of a product tapping demand for both portability and satiation.
Quaker owner PepsiCo has embraced another major food trend this year with the national roll-out of gluten-free Quaker oats following a launch in selected stores late in 2015.
Looking ahead, IRI is expecting further development of products that can bring a clear benefit to consumers, such as high protein content, ingredients such as whole grains, and indulgence.