Though English stress is normally on the first syllable of the word, it can in fact appear on any syllable. It is rather difficult to predict as is also the case in languages such as Russian, German and Portuguese. Sometimes it appears on the final syllable as in "technique", "expertise", "remark" and "unique". In other instances the stress is penultimate as in "transportation", "banana", "tomato" and "establish". Antepenultimate stress occurs in "undoubtedly", "coordinate", "regrettable" and "informative". English stress is thus largely unpredictable.
In many cases, though, affixation produces what can be termed English stress shift. Many roots have a shift in stress when a suffix is attached to them. Though the stress shifts to the following syllable, the position of the stressed syllable in relation to the final syllable remains the same.
To illustrate, the word "economy" consists of four syllables in which the third to last syllable is stressed. The third to last syllable is commonly referred to as the antepenultimate syllable. In the adjective "economical" five syllables are present. Now it is the third syllable which is stressed and not the second as in "economy". However, in both "economy" and "economical", it is the antepenultimate syllable which is stressed.
This same pattern is present in the following words:
In each of the examples, the adjective consists of an additional syllable because of the addition of the suffix. The result is that the stress shifts to the following syllable. However, in relation to the final syllable of the word, the stress pattern remains the same. It is antepenultimate. This rule does not work in all cases, however. For example, the words "behaviour" and "behavioural" do not follow this pattern. However, the stress shift can be observed in many instances.
Stress in English can undoubtedly be difficult to predict as is the case in other languages. Nevertheless, it is true that most English words are stressed on the first syllable and that the English stress shift occurs with a large number of words. It is often the case that the derivation of an adjective from a root by suffixation is subject to the stress shift in which the stress in the adjective shifts to the following syllable but as in the root remains antepenultimate.