Den effektive renten falt; dermed ble terminbeløpet lavt.

Because den effektive renten is in the definite form and means the effective interest rate.

In Norwegian, when a noun is definite and has an adjective, you usually get double definiteness:

• den = the
• effektive = effective
• renten = the interest rate

Compare:

• en effektiv rente = an effective interest rate
• den effektive renten = the effective interest rate

So this is a very normal Norwegian pattern.

Because adjectives usually take -e when they come before a definite noun.

So:

• en effektiv rente = an effective interest rate
• den effektive renten = the effective interest rate

This -e ending is very common with adjectives in definite noun phrases.

Renten is the definite form of rente, which means interest rate or interest depending on context.

Here:

• rente = interest rate / interest
• renten = the interest rate

In this sentence, it most naturally refers to the interest rate.

Falt is the past tense of falle, which means to fall.

So:

• falle = to fall
• falt = fell

Norwegian often uses falle the same way English uses fall or drop for prices, rates, and numbers:

• Renten falt. = The interest rate fell.
• Prisene falt. = Prices fell.

So Den effektive renten falt is a very natural way to say The effective interest rate fell.

Dermed means something like:

• thereby
• thus
• as a result
• consequently

It connects the first part of the sentence to the result in the second part:

• Den effektive renten falt; dermed ble terminbeløpet lavt.

So the idea is: the interest rate fell, and as a result the installment amount became low.

It is a somewhat formal or written-sounding connector, but very common.

Because Norwegian follows the V2 rule in main clauses: the finite verb must come in the second position.

Here, dermed is placed first, so the verb must come right after it:

• Dermed ble terminbeløpet lavt.

Structure:

• Dermed = first element
• ble = finite verb in second position
• terminbeløpet = subject
• lavt = complement

This is a very important Norwegian pattern. Compare:

• Terminbeløpet ble lavt.
• Dermed ble terminbeløpet lavt.
• Da ble terminbeløpet lavt.

When another element comes first, the verb still stays second.

Because ble means became, while var means was.

So:

• ble lavt = became low
• var lavt = was low

In this sentence, the second clause describes a change resulting from the lower interest rate. That is why ble is a better choice:

• the interest rate fell
• therefore the installment amount became low

If you used var, it would focus more on the state, not the change.

Terminbeløpet is a compound noun:

• termin = installment period / payment term
• beløp = amount
• terminbeløpet = the installment amount / the periodic payment amount

This kind of compound is very common in Norwegian. Norwegian often joins words together where English uses separate words.

So this word most likely refers to the amount paid in each payment period, for example on a loan.

Because lavt agrees with the noun terminbeløpet, which is a neuter noun.

The base adjective is lav = low, but adjective forms change depending on gender and grammar:

• en lav pris = a low price
• et lavt beløp = a low amount
• lave priser = low prices

Since beløp is neuter (et beløp), the adjective becomes lavt.

Because beløp is a neuter noun, so its definite singular form takes -et:

• et beløp = an amount
• beløpet = the amount

When it is part of a compound, the same pattern remains:

• et terminbeløp = an installment amount
• terminbeløpet = the installment amount

If it were a common-gender noun (en noun), the definite ending would usually be -en instead.

The semicolon links two closely related main clauses:

• Den effektive renten falt
• dermed ble terminbeløpet lavt

It shows that the second clause is a direct consequence of the first. In Norwegian, this punctuation works much like it does in English.

You could also write it with a period:

• Den effektive renten falt. Dermed ble terminbeløpet lavt.

That would also be correct.

It sounds fairly neutral to formal, especially because of:

• dermed
• the financial vocabulary effektive renten
• terminbeløpet

So it feels natural in contexts like:

• banking
• finance
• contracts
• news
• written explanations

In casual speech, someone might choose simpler wording, but this sentence is completely normal Norwegian.